diff --git a/changelog/fix_a_false_positive_for_style_access_modifier_declarations.md b/changelog/fix_a_false_positive_for_style_access_modifier_declarations.md
new file mode 100644
index 00000000000..7996c77d955
--- /dev/null
+++ b/changelog/fix_a_false_positive_for_style_access_modifier_declarations.md
@@ -0,0 +1 @@
+* [#5953](https://github.com/rubocop/rubocop/issues/5953): Fix a false positive for `Style/AccessModifierDeclarations` when using `module_function` with symbol. ([@koic][])
diff --git a/lib/rubocop/cop/style/access_modifier_declarations.rb b/lib/rubocop/cop/style/access_modifier_declarations.rb
index 58c4ece37b1..259c22ed3ab 100644
--- a/lib/rubocop/cop/style/access_modifier_declarations.rb
+++ b/lib/rubocop/cop/style/access_modifier_declarations.rb
@@ -79,7 +79,7 @@ class AccessModifierDeclarations < Base
 
         # @!method access_modifier_with_symbol?(node)
         def_node_matcher :access_modifier_with_symbol?, <<~PATTERN
-          (send nil? {:private :protected :public} (sym _))
+          (send nil? {:private :protected :public :module_function} (sym _))
         PATTERN
 
         def on_send(node)
diff --git a/spec/rubocop/cop/style/access_modifier_declarations_spec.rb b/spec/rubocop/cop/style/access_modifier_declarations_spec.rb
index e89a2f5dfe3..f379daede8d 100644
--- a/spec/rubocop/cop/style/access_modifier_declarations_spec.rb
+++ b/spec/rubocop/cop/style/access_modifier_declarations_spec.rb
@@ -46,7 +46,7 @@ class Foo
       }
     end
 
-    %w[private protected public].each do |access_modifier|
+    %w[private protected public module_function].each do |access_modifier|
       it "offends when #{access_modifier} is inlined with a method" do
         expect_offense(<<~RUBY, access_modifier: access_modifier)
           class Test
@@ -108,7 +108,7 @@ class TestThree
       }
     end
 
-    %w[private protected public].each do |access_modifier|
+    %w[private protected public module_function].each do |access_modifier|
       it "offends when #{access_modifier} is not inlined" do
         expect_offense(<<~RUBY, access_modifier: access_modifier)
           class Test