diff --git a/.github/workflows/format.yml b/.github/workflows/format.yml
index 3c1ef571..139d0134 100644
--- a/.github/workflows/format.yml
+++ b/.github/workflows/format.yml
@@ -22,6 +22,6 @@ jobs:
         python -m pip install --upgrade pip
         python -m pip install poetry
         poetry install
-    - name: Run yapf and isort
+    - name: Run yapf, isort, and flake8
       run: |
-        poetry run tox -e yapf,isort
+        poetry run tox -e yapf,isort,flake8
diff --git a/gokart/__init__.py b/gokart/__init__.py
index c0700a7b..2fe85da3 100644
--- a/gokart/__init__.py
+++ b/gokart/__init__.py
@@ -1,10 +1,10 @@
-from gokart.build import build
-from gokart.info import make_tree_info, tree_info
-from gokart.pandas_type_config import PandasTypeConfig
-from gokart.parameter import ExplicitBoolParameter, ListTaskInstanceParameter, TaskInstanceParameter
-from gokart.run import run
-from gokart.task import TaskOnKart
-from gokart.testing import test_run
-from gokart.tree.task_info import make_task_info_as_tree_str
-from gokart.utils import add_config
-from gokart.workspace_management import delete_local_unnecessary_outputs
+from gokart.build import build  # noqa:F401
+from gokart.info import make_tree_info, tree_info  # noqa:F401
+from gokart.pandas_type_config import PandasTypeConfig  # noqa:F401
+from gokart.parameter import ExplicitBoolParameter, ListTaskInstanceParameter, TaskInstanceParameter  # noqa:F401
+from gokart.run import run  # noqa:F401
+from gokart.task import TaskOnKart  # noqa:F401
+from gokart.testing import test_run  # noqa:F401
+from gokart.tree.task_info import make_task_info_as_tree_str  # noqa:F401
+from gokart.utils import add_config  # noqa:F401
+from gokart.workspace_management import delete_local_unnecessary_outputs  # noqa:F401
diff --git a/gokart/build.py b/gokart/build.py
index 4875f04f..7662cfa5 100644
--- a/gokart/build.py
+++ b/gokart/build.py
@@ -1,5 +1,4 @@
 import logging
-import sys
 from logging import getLogger
 from typing import Any, Optional
 
diff --git a/gokart/file_processor.py b/gokart/file_processor.py
index b23855aa..90f8d96f 100644
--- a/gokart/file_processor.py
+++ b/gokart/file_processor.py
@@ -168,7 +168,7 @@ def load(self, file):
 
     def dump(self, obj, file):
         assert isinstance(obj, pd.DataFrame) or isinstance(obj, pd.Series) or isinstance(obj, dict), \
-           f'requires pd.DataFrame or pd.Series or dict, but {type(obj)} is passed.'
+            f'requires pd.DataFrame or pd.Series or dict, but {type(obj)} is passed.'
         if isinstance(obj, dict):
             obj = pd.DataFrame.from_dict(obj)
         obj.to_json(file)
diff --git a/gokart/info.py b/gokart/info.py
index 47449861..8c42d0fa 100644
--- a/gokart/info.py
+++ b/gokart/info.py
@@ -1,6 +1,5 @@
-import warnings
 from logging import getLogger
-from typing import List, NamedTuple, Optional, Set, Tuple
+from typing import List, Optional, Set
 
 import luigi
 
diff --git a/gokart/object_storage.py b/gokart/object_storage.py
index 462d701a..f867c82e 100644
--- a/gokart/object_storage.py
+++ b/gokart/object_storage.py
@@ -3,7 +3,7 @@
 import luigi
 import luigi.contrib.gcs
 import luigi.contrib.s3
-from luigi.format import FileWrapper, Format
+from luigi.format import Format
 
 from gokart.gcs_config import GCSConfig
 from gokart.gcs_zip_client import GCSZipClient
diff --git a/gokart/slack/__init__.py b/gokart/slack/__init__.py
index 6c84daea..b916bcf5 100644
--- a/gokart/slack/__init__.py
+++ b/gokart/slack/__init__.py
@@ -1,3 +1,3 @@
-from gokart.slack.event_aggregator import EventAggregator
-from gokart.slack.slack_api import SlackAPI
-from gokart.slack.slack_config import SlackConfig
+from gokart.slack.event_aggregator import EventAggregator  # noqa:F401
+from gokart.slack.slack_api import SlackAPI  # noqa:F401
+from gokart.slack.slack_config import SlackConfig  # noqa:F401
diff --git a/gokart/task.py b/gokart/task.py
index 0760113f..53547cef 100644
--- a/gokart/task.py
+++ b/gokart/task.py
@@ -150,7 +150,7 @@ def clone(self, cls=None, **kwargs):
             cls = self.__class__
 
         new_k = {}
-        for param_name, param_class in cls.get_params():
+        for param_name, _ in cls.get_params():
             if param_name in kwargs:
                 new_k[param_name] = kwargs[param_name]
             elif hasattr(self, param_name) and (param_name not in _SPECIAL_PARAMS):
diff --git a/gokart/testing/__init__.py b/gokart/testing/__init__.py
index 38a7f226..c7359e97 100644
--- a/gokart/testing/__init__.py
+++ b/gokart/testing/__init__.py
@@ -1,2 +1,2 @@
-from gokart.testing.check_if_run_with_empty_data_frame import test_run, try_to_run_test_for_empty_data_frame
-from gokart.testing.pandas_assert import assert_frame_contents_equal
+from gokart.testing.check_if_run_with_empty_data_frame import test_run, try_to_run_test_for_empty_data_frame  # noqa:F401
+from gokart.testing.pandas_assert import assert_frame_contents_equal  # noqa:F401
diff --git a/gokart/tree/task_info.py b/gokart/tree/task_info.py
index bb9c3e20..97cfde57 100644
--- a/gokart/tree/task_info.py
+++ b/gokart/tree/task_info.py
@@ -1,9 +1,6 @@
 import os
-import warnings
-from dataclasses import dataclass
-from typing import List, Optional, Set
+from typing import List, Optional
 
-import luigi
 import pandas as pd
 
 from gokart.target import make_target
@@ -46,7 +43,7 @@ def make_task_info_as_table(task: TaskOnKart, ignore_task_names: Optional[List[s
         List of task names to ignore.
     Returns
     -------
-    - task_info_table : pandas.DataFrame 
+    - task_info_table : pandas.DataFrame
         Formatted task dependency table.
     """
 
diff --git a/gokart/tree/task_info_formatter.py b/gokart/tree/task_info_formatter.py
index 924f431e..30bb9ed9 100644
--- a/gokart/tree/task_info_formatter.py
+++ b/gokart/tree/task_info_formatter.py
@@ -1,7 +1,7 @@
 import typing
 import warnings
 from dataclasses import dataclass
-from typing import Dict, Iterable, List, NamedTuple, Optional, Set, Union
+from typing import Dict, List, NamedTuple, Optional, Set, Union
 
 import luigi
 
diff --git a/gokart/workspace_management.py b/gokart/workspace_management.py
index 3a0d3dcd..d9d57624 100644
--- a/gokart/workspace_management.py
+++ b/gokart/workspace_management.py
@@ -24,7 +24,7 @@ def delete_local_unnecessary_outputs(task: gokart.TaskOnKart):
     necessary_files = set(_get_all_output_file_paths(task))
     unnecessary_files = all_files - necessary_files - log_files
     if len(unnecessary_files) == 0:
-        logger.info(f'all files are necessary for this task.')
+        logger.info('all files are necessary for this task.')
     else:
         logger.info(f'remove following files: {os.linesep} {os.linesep.join(unnecessary_files)}')
     for file in unnecessary_files:
diff --git a/poetry.lock b/poetry.lock
index 6c77d8d6..cfe7368d 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -74,18 +74,18 @@ tzdata = ["tzdata"]
 
 [[package]]
 name = "boto3"
-version = "1.26.42"
+version = "1.26.45"
 description = "The AWS SDK for Python"
 category = "main"
 optional = false
 python-versions = ">= 3.7"
 files = [
-    {file = "boto3-1.26.42-py3-none-any.whl", hash = "sha256:75c995a04723f23e35e16ea491ed91a1345e2fa6492678a216488512308dada1"},
-    {file = "boto3-1.26.42.tar.gz", hash = "sha256:4cfd7e05e4033dbca2cc59bcfdafbdaef9d83dc3c0448917569b301d85766d9d"},
+    {file = "boto3-1.26.45-py3-none-any.whl", hash = "sha256:b1bc7db503dc49bdccf5dada080077056a32af9982afdde84578a109cd741d05"},
+    {file = "boto3-1.26.45.tar.gz", hash = "sha256:cc7f652df93e1ce818413fd82ffd645d4f92a64fec67c72946212d3750eaa80f"},
 ]
 
 [package.dependencies]
-botocore = ">=1.29.42,<1.30.0"
+botocore = ">=1.29.45,<1.30.0"
 jmespath = ">=0.7.1,<2.0.0"
 s3transfer = ">=0.6.0,<0.7.0"
 
@@ -94,14 +94,14 @@ crt = ["botocore[crt] (>=1.21.0,<2.0a0)"]
 
 [[package]]
 name = "botocore"
-version = "1.29.42"
+version = "1.29.45"
 description = "Low-level, data-driven core of boto 3."
 category = "main"
 optional = false
 python-versions = ">= 3.7"
 files = [
-    {file = "botocore-1.29.42-py3-none-any.whl", hash = "sha256:f52f9dbd7ad42b3528c1052086c1a7b6122a018f919afdb604f2889caefe8092"},
-    {file = "botocore-1.29.42.tar.gz", hash = "sha256:d05c62f64e76194c40f598f5f7c804ec50d9820e9f03f6e0198558e4ace167c4"},
+    {file = "botocore-1.29.45-py3-none-any.whl", hash = "sha256:a5c0e13f266ee9a74335a1e5d3e377f2baae27226ae23d78f023bae0d18f3161"},
+    {file = "botocore-1.29.45.tar.gz", hash = "sha256:62ae03e591ff25555854aa338da35190ffe18c0b1be2ebf5cfb277164233691f"},
 ]
 
 [package.dependencies]
@@ -343,63 +343,63 @@ test-no-codebase = ["Pillow", "matplotlib", "pytest"]
 
 [[package]]
 name = "coverage"
-version = "7.0.2"
+version = "7.0.4"
 description = "Code coverage measurement for Python"
 category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
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-    {file = "coverage-7.0.2-cp310-cp310-macosx_11_0_arm64.whl", hash = "sha256:a2d4f68e4fa286fb6b00d58a1e87c79840e289d3f6e5dcb912ad7b0fbd9629fb"},
-    {file = "coverage-7.0.2-cp310-cp310-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:426895ac9f2938bec193aa998e7a77a3e65d3e46903f348e794b4192b9a5b61e"},
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 ]
 
 [package.extras]
@@ -521,6 +521,23 @@ files = [
 docs = ["furo (>=2022.12.7)", "sphinx (>=5.3)", "sphinx-autodoc-typehints (>=1.19.5)"]
 testing = ["covdefaults (>=2.2.2)", "coverage (>=7.0.1)", "pytest (>=7.2)", "pytest-cov (>=4)", "pytest-timeout (>=2.1)"]
 
+[[package]]
+name = "flake8"
+version = "5.0.4"
+description = "the modular source code checker: pep8 pyflakes and co"
+category = "dev"
+optional = false
+python-versions = ">=3.6.1"
+files = [
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+]
+
+[package.dependencies]
+mccabe = ">=0.7.0,<0.8.0"
+pycodestyle = ">=2.9.0,<2.10.0"
+pyflakes = ">=2.5.0,<2.6.0"
+
 [[package]]
 name = "fonttools"
 version = "4.38.0"
@@ -572,14 +589,14 @@ grpcio-gcp = ["grpcio-gcp (>=0.2.2,<1.0dev)"]
 
 [[package]]
 name = "google-api-python-client"
-version = "2.70.0"
+version = "2.71.0"
 description = "Google API Client Library for Python"
 category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
-    {file = "google-api-python-client-2.70.0.tar.gz", hash = "sha256:262de094d5a30d337f59e66581019fed45b698c078397ac48dd323c0968236e7"},
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 ]
 
 [package.dependencies]
@@ -632,14 +649,14 @@ six = "*"
 
 [[package]]
 name = "googleapis-common-protos"
-version = "1.57.0"
+version = "1.57.1"
 description = "Common protobufs used in Google APIs"
 category = "main"
 optional = false
 python-versions = ">=3.7"
 files = [
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 ]
 
 [package.dependencies]
@@ -1032,16 +1049,28 @@ pyparsing = ">=2.2.1"
 python-dateutil = ">=2.7"
 setuptools_scm = ">=7"
 
+[[package]]
+name = "mccabe"
+version = "0.7.0"
+description = "McCabe checker, plugin for flake8"
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+files = [
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+    {file = "mccabe-0.7.0.tar.gz", hash = "sha256:348e0240c33b60bbdf4e523192ef919f28cb2c3d7d5c7794f74009290f236325"},
+]
+
 [[package]]
 name = "moto"
-version = "4.0.12"
+version = "4.0.13"
 description = "A library that allows your python tests to easily mock out the boto library"
 category = "dev"
 optional = false
 python-versions = ">=3.6"
 files = [
-    {file = "moto-4.0.12-py3-none-any.whl", hash = "sha256:e6592727d90a2dc82ca7c7fa61b224e2b195cc0dcdac2f46ccbf0cd8efde1459"},
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+    {file = "moto-4.0.13-py3-none-any.whl", hash = "sha256:e73400c6d3fe06028aa7f07bb6f276f14260d289b70f38928a98e3d3d968352d"},
+    {file = "moto-4.0.13.tar.gz", hash = "sha256:baf7d6969cf837990c730e6e648315bebc2e1c0038d9d8fc4f59d03561484469"},
 ]
 
 [package.dependencies]
@@ -1376,6 +1405,18 @@ files = [
 [package.dependencies]
 pyasn1 = ">=0.4.6,<0.5.0"
 
+[[package]]
+name = "pycodestyle"
+version = "2.9.1"
+description = "Python style guide checker"
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+files = [
+    {file = "pycodestyle-2.9.1-py2.py3-none-any.whl", hash = "sha256:d1735fc58b418fd7c5f658d28d943854f8a849b01a5d0a1e6f3f3fdd0166804b"},
+    {file = "pycodestyle-2.9.1.tar.gz", hash = "sha256:2c9607871d58c76354b697b42f5d57e1ada7d261c261efac224b664affdc5785"},
+]
+
 [[package]]
 name = "pycparser"
 version = "2.21"
@@ -1388,6 +1429,18 @@ files = [
     {file = "pycparser-2.21.tar.gz", hash = "sha256:e644fdec12f7872f86c58ff790da456218b10f863970249516d60a5eaca77206"},
 ]
 
+[[package]]
+name = "pyflakes"
+version = "2.5.0"
+description = "passive checker of Python programs"
+category = "dev"
+optional = false
+python-versions = ">=3.6"
+files = [
+    {file = "pyflakes-2.5.0-py2.py3-none-any.whl", hash = "sha256:4579f67d887f804e67edb544428f264b7b24f435b263c4614f384135cea553d2"},
+    {file = "pyflakes-2.5.0.tar.gz", hash = "sha256:491feb020dca48ccc562a8c0cbe8df07ee13078df59813b83959cbdada312ea3"},
+]
+
 [[package]]
 name = "pyparsing"
 version = "3.0.9"
@@ -1405,14 +1458,14 @@ diagrams = ["jinja2", "railroad-diagrams"]
 
 [[package]]
 name = "pyproject-api"
-version = "1.3.0"
+version = "1.4.0"
 description = "API to interact with the python pyproject.toml based projects"
 category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
-    {file = "pyproject_api-1.3.0-py3-none-any.whl", hash = "sha256:90d8ce5f7231dce7cdeedbda1568e3cd427ca0cb4cf56f3d936f61d7eca9cde0"},
-    {file = "pyproject_api-1.3.0.tar.gz", hash = "sha256:6da9b5fcad6f6bdcf88ee0dbc6cc41783e377ceb6767b5004881ecb50ae6d6e7"},
+    {file = "pyproject_api-1.4.0-py3-none-any.whl", hash = "sha256:c34226297781efdd1ba4dfb74ce21076d9a8360e2125ea31803c1a02c76b2460"},
+    {file = "pyproject_api-1.4.0.tar.gz", hash = "sha256:ac85c1f82e0291dbae5a7739dbb9a990e11ee4034c9b5599ea714f07a24ecd71"},
 ]
 
 [package.dependencies]
@@ -1423,6 +1476,22 @@ tomli = {version = ">=2.0.1", markers = "python_version < \"3.11\""}
 docs = ["furo (>=2022.9.29)", "sphinx (>=5.3)", "sphinx-autodoc-typehints (>=1.19.5)"]
 testing = ["covdefaults (>=2.2.2)", "importlib-metadata (>=5.1)", "pytest (>=7.2)", "pytest-cov (>=4)", "pytest-mock (>=3.10)", "virtualenv (>=20.17)", "wheel (>=0.38.4)"]
 
+[[package]]
+name = "pyproject-flake8"
+version = "5.0.4"
+description = "pyproject-flake8 (`pflake8`), a monkey patching wrapper to connect flake8 with pyproject.toml configuration"
+category = "dev"
+optional = false
+python-versions = "*"
+files = [
+    {file = "pyproject-flake8-5.0.4.tar.gz", hash = "sha256:cb69b064b39bb588b5c45a7b16c158f013dddb2ce41cf1896f4b8bc7839bd2ce"},
+    {file = "pyproject_flake8-5.0.4-py2.py3-none-any.whl", hash = "sha256:b41bf2a8f8590220ae067ba4f1c4ab43b4efc65bb76fac18aa982dadea223c08"},
+]
+
+[package.dependencies]
+flake8 = "5.0.4"
+tomli = {version = "*", markers = "python_version < \"3.11\""}
+
 [[package]]
 name = "python-daemon"
 version = "2.3.2"
@@ -1740,14 +1809,14 @@ files = [
 
 [[package]]
 name = "tox"
-version = "4.1.3"
+version = "4.2.6"
 description = "tox is a generic virtualenv management and test command line tool"
 category = "dev"
 optional = false
 python-versions = ">=3.7"
 files = [
-    {file = "tox-4.1.3-py3-none-any.whl", hash = "sha256:f1840b1698e5187d4c3bae4fe41332c2f3fedde3b6773474899f9e0b329a41dd"},
-    {file = "tox-4.1.3.tar.gz", hash = "sha256:9976b41def48a5a2dce477de2c90c8231a5166829aaca916d0952ec4d7429f43"},
+    {file = "tox-4.2.6-py3-none-any.whl", hash = "sha256:fb79b3e4b788491949576a9c80c2d56419eac994567c3591e24bb2788b5901d0"},
+    {file = "tox-4.2.6.tar.gz", hash = "sha256:ecf224a4f3a318adcdd71aa8fe15ffd31f14afd6a9845a43ffd63950a7325538"},
 ]
 
 [package.dependencies]
@@ -1939,4 +2008,4 @@ files = [
 [metadata]
 lock-version = "2.0"
 python-versions = ">=3.8,<3.11"
-content-hash = "64bf4bfc6362a59ee2844bd4520d87a8a973e0caecd07ebcf09c0cf6aae438dc"
+content-hash = "4b68f87b2b8e92de5680588303fe390ee58bfdb9736bfa45797f2f2fadaa6628"
diff --git a/pyproject.toml b/pyproject.toml
index 5b0f28fd..3f776426 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,6 +9,7 @@ homepage = "https://github.com/m3dev/gokart"
 repository = "https://github.com/m3dev/gokart"
 documentation = "https://gokart.readthedocs.io/en/latest/"
 
+
 [tool.poetry-dynamic-versioning]
 enable = true
 style = "pep440"
@@ -30,7 +31,8 @@ APScheduler = "*"
 redis = "*"
 matplotlib = "*"
 
-[tool.poetry.dev-dependencies]
+[tool.poetry.group.dev.dependencies]
+pyproject-flake8 = "5.0.4"
 tox = "*"
 moto = "*"
 testfixtures = "*"
@@ -41,6 +43,13 @@ toml = "*"
 lupa = "*"
 fakeredis = "*"
 
+[tool.flake8]
+# B006: Do not use mutable data structures for argument defaults. They are created during function definition time. All calls to the function reuse this one instance of that data structure, persisting changes between them.
+# B008 Do not perform function calls in argument defaults.  The call is performed only once at function definition time. All calls to your function will reuse the result of that definition-time function call.  If this is intended, assign the function call to a module-level variable and use that variable as a default value.
+ignore = "B006,B008"
+max-line-length = 160
+exclude = "venv/*,tox/*"
+
 [tool.yapf]
 based_on_style = "pep8"
 column_limit = 160
diff --git a/test/__init__.py b/test/__init__.py
index 8b137891..e69de29b 100644
--- a/test/__init__.py
+++ b/test/__init__.py
@@ -1 +0,0 @@
-
diff --git a/test/slack/__init__.py b/test/slack/__init__.py
index 8b137891..e69de29b 100644
--- a/test/slack/__init__.py
+++ b/test/slack/__init__.py
@@ -1 +0,0 @@
-
diff --git a/test/slack/test_slack_api.py b/test/slack/test_slack_api.py
index 9205f812..2700567b 100644
--- a/test/slack/test_slack_api.py
+++ b/test/slack/test_slack_api.py
@@ -34,9 +34,9 @@ def _conversations_list(params={}):
         mock_client.conversations_list = MagicMock(side_effect=_conversations_list)
         patch.return_value = mock_client
 
-        with LogCapture() as l:
+        with LogCapture() as log:
             gokart.slack.SlackAPI(token='invalid', channel='test', to_user='test user')
-            l.check(('gokart.slack.slack_api', 'WARNING', 'The job will start without slack notification: Channel test is not found in public channels.'))
+            log.check(('gokart.slack.slack_api', 'WARNING', 'The job will start without slack notification: Channel test is not found in public channels.'))
 
     @mock.patch('gokart.slack.slack_api.slack_sdk.WebClient')
     def test_invalid_channel(self, patch):
@@ -58,10 +58,10 @@ def _conversations_list(params={}):
         mock_client.conversations_list = MagicMock(side_effect=_conversations_list)
         patch.return_value = mock_client
 
-        with LogCapture() as l:
+        with LogCapture() as log:
             gokart.slack.SlackAPI(token='valid', channel='invalid_channel', to_user='test user')
-            l.check(('gokart.slack.slack_api', 'WARNING',
-                     'The job will start without slack notification: Channel invalid_channel is not found in public channels.'))
+            log.check(('gokart.slack.slack_api', 'WARNING',
+                       'The job will start without slack notification: Channel invalid_channel is not found in public channels.'))
 
     @mock.patch('gokart.slack.slack_api.slack_sdk.WebClient')
     def test_send_snippet_with_invalid_token(self, patch):
@@ -88,10 +88,11 @@ def _api_call(method, data={}):
         mock_client.api_call = MagicMock(side_effect=_api_call)
         patch.return_value = mock_client
 
-        with LogCapture() as l:
+        with LogCapture() as log:
             api = gokart.slack.SlackAPI(token='valid', channel='valid', to_user='test user')
             api.send_snippet(comment='test', title='title', content='content')
-            l.check(('gokart.slack.slack_api', 'WARNING', 'Failed to send slack notification: Error while uploading file. The error reason is "error_reason".'))
+            log.check(
+                ('gokart.slack.slack_api', 'WARNING', 'Failed to send slack notification: Error while uploading file. The error reason is "error_reason".'))
 
     @mock.patch('gokart.slack.slack_api.slack_sdk.WebClient')
     def test_send(self, patch):
diff --git a/test/test_run.py b/test/test_run.py
index 5e573d42..cd640c60 100644
--- a/test/test_run.py
+++ b/test/test_run.py
@@ -7,7 +7,6 @@
 
 import gokart
 from gokart.run import _try_to_send_event_summary_to_slack
-from gokart.slack import SlackConfig
 
 
 class _DummyTask(gokart.TaskOnKart):
@@ -35,7 +34,7 @@ def test_run(self):
     def test_run_with_undefined_environ(self):
         config_file_path = os.path.join(os.path.dirname(__name__), 'config', 'test_config.ini')
         luigi.configuration.LuigiConfigParser.add_config_path(config_file_path)
-        with self.assertRaises(luigi.parameter.MissingParameterException) as missing_parameter:
+        with self.assertRaises(luigi.parameter.MissingParameterException):
             gokart.run()
 
     @patch('sys.argv',
diff --git a/test/test_s3_config.py b/test/test_s3_config.py
index c4c42bbf..dd74b911 100644
--- a/test/test_s3_config.py
+++ b/test/test_s3_config.py
@@ -1,6 +1,4 @@
-import os
 import unittest
-from unittest.mock import MagicMock, mock_open, patch
 
 from gokart.s3_config import S3Config
 
diff --git a/test/test_task_on_kart.py b/test/test_task_on_kart.py
index 02b09e07..66e3c49b 100644
--- a/test/test_task_on_kart.py
+++ b/test/test_task_on_kart.py
@@ -335,7 +335,7 @@ def test_load_generator_with_single_target(self):
         data = [x for x in task.load_generator()]
         self.assertEqual(data, [[1, 2]])
 
-    def test_load_with_keyword(self):
+    def test_load_generator_with_keyword(self):
         task = _DummyTask()
         target = MagicMock(spec=TargetOnKart)
         target.load.return_value = [1, 2]
@@ -501,7 +501,7 @@ def test_repr(self):
                                                                _DummySubTaskWithPrivateParameter()])
         sub_task_id = _DummySubTaskWithPrivateParameter().make_unique_id()
         expected = f'{__name__}._DummyTaskWithPrivateParameter(int_param=1, private_int_param=1, task_param={__name__}._DummySubTaskWithPrivateParameter({sub_task_id}), ' \
-            f'list_task_param=[{__name__}._DummySubTaskWithPrivateParameter({sub_task_id}), {__name__}._DummySubTaskWithPrivateParameter({sub_task_id})])'
+            f'list_task_param=[{__name__}._DummySubTaskWithPrivateParameter({sub_task_id}), {__name__}._DummySubTaskWithPrivateParameter({sub_task_id})])'  # noqa:E501
         self.assertEqual(expected, repr(task))
 
     def test_str(self):
diff --git a/test/testing/__init__.py b/test/testing/__init__.py
index 8b137891..e69de29b 100644
--- a/test/testing/__init__.py
+++ b/test/testing/__init__.py
@@ -1 +0,0 @@
-
diff --git a/test/tree/test_task_info_formatter.py b/test/tree/test_task_info_formatter.py
index fb45d444..2fa9ddf2 100644
--- a/test/tree/test_task_info_formatter.py
+++ b/test/tree/test_task_info_formatter.py
@@ -1,7 +1,5 @@
 import unittest
 
-import pandas as pd
-
 import gokart
 from gokart.tree.task_info_formatter import RequiredTask, _make_requires_info
 
@@ -25,9 +23,12 @@ def test_make_requires_info_with_list(self):
         self.assertEqual(resulted, expected)
 
     def test_make_requires_info_with_generator(self):
-        requires_gen = lambda: (_RequiredTaskExampleTaskA() for _ in range(2))
-        resulted = _make_requires_info(requires=requires_gen())
-        expected = [RequiredTask(name=require.__class__.__name__, unique_id=require.make_unique_id()) for require in requires_gen()]
+
+        def _requires_gen():
+            return (_RequiredTaskExampleTaskA() for _ in range(2))
+
+        resulted = _make_requires_info(requires=_requires_gen())
+        expected = [RequiredTask(name=require.__class__.__name__, unique_id=require.make_unique_id()) for require in _requires_gen()]
         self.assertEqual(resulted, expected)
 
     def test_make_requires_info_with_dict(self):
diff --git a/tox.ini b/tox.ini
index 86e92a50..84485d2a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py{38,39,310,311,yapf,isort}
+envlist = py{38,39,310,311,yapf,isort,flake8}
 isolated_build = true
 
 [testenv]
@@ -17,6 +17,11 @@ allowlist_externals = isort
 skip_install = true
 commands = isort -c gokart test {posargs}
 
+[testenv:flake8]
+allowlist_externals = pflake8
+skip_install = true
+commands = pflake8 gokart test {posargs}
+
 [gh-actions]
 python =
     3.8: py38