diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 3da5b830..ae9c1c6d 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -91,7 +91,7 @@ $ pip install -r requirements.txt
 $ flake8
 $ black --check .
 $ isort . --check
-$ mypy .
+$ mypy optuna_dashboard python_tests
 ```
 
 or