diff --git a/.github/workflows/python-tests.yml b/.github/workflows/python-tests.yml
index e1b320cc..c01e0161 100644
--- a/.github/workflows/python-tests.yml
+++ b/.github/workflows/python-tests.yml
@@ -21,7 +21,8 @@ jobs:
           python -m pip install --upgrade pip setuptools
           pip install --progress-bar off .[lint]
       - run: flake8 . --show-source
-      - run: black --check .
+      - run: black --check --diff .
+      - run: isort --check --diff .
       - run: mypy .
   test:
     runs-on: ubuntu-latest
diff --git a/DEVELOPMENT.md b/DEVELOPMENT.md
index bed40c4c..453c698b 100644
--- a/DEVELOPMENT.md
+++ b/DEVELOPMENT.md
@@ -76,6 +76,7 @@ $ tox -e py39
 $ pip install .[lint]
 $ flake8
 $ black --check .
+$ isort . --check
 $ mypy .
 ```
 
diff --git a/optuna_dashboard/app.py b/optuna_dashboard/app.py
index 97af477e..241dd5dd 100644
--- a/optuna_dashboard/app.py
+++ b/optuna_dashboard/app.py
@@ -1,22 +1,39 @@
-from datetime import datetime, timedelta
+from datetime import datetime
+from datetime import timedelta
 import functools
 import json
 import logging
 import os
 import threading
 import traceback
-from typing import Union, Dict, List, Optional, TypeVar, Callable, Any, cast
+from typing import Any
+from typing import Callable
+from typing import cast
+from typing import Dict
+from typing import List
+from typing import Optional
+from typing import TypeVar
+from typing import Union
 
-from bottle import Bottle, BaseResponse, redirect, request, response, static_file
+from bottle import BaseResponse
+from bottle import Bottle
+from bottle import redirect
+from bottle import request
+from bottle import response
+from bottle import static_file
 import optuna
 from optuna.exceptions import DuplicatedStudyError
 from optuna.storages import BaseStorage
-from optuna.trial import FrozenTrial, TrialState
-from optuna.study import StudyDirection, StudySummary, Study
+from optuna.study import Study
+from optuna.study import StudyDirection
+from optuna.study import StudySummary
+from optuna.trial import FrozenTrial
+from optuna.trial import TrialState
 
 from . import serializer
 from .search_space import get_search_space
 
+
 BottleViewReturn = Union[str, bytes, Dict[str, Any], BaseResponse]
 BottleView = TypeVar("BottleView", bound=Callable[..., BottleViewReturn])
 
diff --git a/optuna_dashboard/search_space.py b/optuna_dashboard/search_space.py
index 1f740fde..ff7d9eb3 100644
--- a/optuna_dashboard/search_space.py
+++ b/optuna_dashboard/search_space.py
@@ -1,9 +1,15 @@
 import copy
 import threading
-from typing import Dict, List, Optional, Set, Tuple
+from typing import Dict
+from typing import List
+from typing import Optional
+from typing import Set
+from typing import Tuple
 
 from optuna.distributions import BaseDistribution
-from optuna.trial import TrialState, FrozenTrial
+from optuna.trial import FrozenTrial
+from optuna.trial import TrialState
+
 
 SearchSpaceSetT = Set[Tuple[str, BaseDistribution]]
 SearchSpaceListT = List[Tuple[str, BaseDistribution]]
diff --git a/optuna_dashboard/serializer.py b/optuna_dashboard/serializer.py
index 7b05bf22..ce407f52 100644
--- a/optuna_dashboard/serializer.py
+++ b/optuna_dashboard/serializer.py
@@ -1,9 +1,13 @@
-from typing import Any, Dict, List, Tuple
+from typing import Any
+from typing import Dict
+from typing import List
+from typing import Tuple
 
 from optuna.distributions import BaseDistribution
 from optuna.study import StudySummary
 from optuna.trial import FrozenTrial
 
+
 try:
     from typing import TypedDict
 except ImportError:
diff --git a/setup.cfg b/setup.cfg
index dc10a76f..1ae34112 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -35,6 +35,7 @@ install_requires =
 [options.extras_require]
 lint =
     black
+    isort
     mypy
     flake8
 
@@ -56,4 +57,15 @@ exclude = venv,build,.tox
 
 [mypy]
 ignore_missing_imports = True
-disallow_untyped_defs = True
\ No newline at end of file
+disallow_untyped_defs = True
+
+[isort]
+profile = black
+src_paths =
+    optuna_dashboard
+    tests
+line_length = 99
+lines_after_imports = 2
+force_single_line = True
+force_sort_within_sections = True
+order_by_type = False
diff --git a/setup.py b/setup.py
index 7f1a1763..26e08e48 100644
--- a/setup.py
+++ b/setup.py
@@ -1,4 +1,5 @@
 from setuptools import setup
 
+
 if __name__ == "__main__":
     setup()
diff --git a/tests/test_api.py b/tests/test_api.py
index 3226ecc5..0c3cd8c9 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -2,7 +2,9 @@ import json
 from unittest import TestCase
 
 import optuna
+
 from optuna_dashboard.app import create_app
+
 from .wsgi_client import send_request
 
 
diff --git a/tests/test_search_space.py b/tests/test_search_space.py
index 61a34e63..597af5d9 100644
--- a/tests/test_search_space.py
+++ b/tests/test_search_space.py
@@ -1,5 +1,5 @@
-import warnings
 from unittest import TestCase
+import warnings
 
 import optuna
 from optuna import create_trial
diff --git a/tests/test_serializers.py b/tests/test_serializers.py
index d95f6f9a..1137d9e2 100644
--- a/tests/test_serializers.py
+++ b/tests/test_serializers.py
@@ -1,4 +1,5 @@
 from unittest import TestCase
+
 from optuna_dashboard.serializer import serialize_attrs
 
 
diff --git a/tests/wsgi_client.py b/tests/wsgi_client.py
index d6975951..68a4c0e1 100644
--- a/tests/wsgi_client.py
+++ b/tests/wsgi_client.py
@@ -1,5 +1,13 @@
 import io
-from typing import Dict, Optional, Union, Any, Tuple, List, Callable, Iterable
+from typing import Any
+from typing import Callable
+from typing import Dict
+from typing import Iterable
+from typing import List
+from typing import Optional
+from typing import Tuple
+from typing import Union
+
 
 WSGIEnv = Dict[str, Any]  # Cannot use TypedDict because of 'HTTP_' variables
 StartResponse = Callable[[str, List[Tuple[str, str]]], None]
diff --git a/tox.ini b/tox.ini
index fbe8bf5d..dd77fb99 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,6 +6,7 @@ envlist =
     py39
     flake8
     black
+    isort
     mypy
 
 [testenv:py36]
@@ -32,6 +33,10 @@ commands = flake8 . {posargs}
 deps = black
 commands = black --check . {posargs}
 
+[testenv:isort]
+deps = isort
+commands = isort . --check
+
 [testenv:mypy]
 deps = mypy
 commands = mypy . {posargs}
diff --git a/visual_regression_test.py b/visual_regression_test.py
index 84fbdf8f..e108cd5a 100644
--- a/visual_regression_test.py
+++ b/visual_regression_test.py
@@ -1,13 +1,16 @@
 import asyncio
+import os
 import threading
 import time
+from typing import List
+from typing import Tuple
+from wsgiref.simple_server import make_server
+
 import optuna
-import os
+from pyppeteer import launch
 
 from optuna_dashboard.app import create_app
-from pyppeteer import launch
-from typing import List, Tuple
-from wsgiref.simple_server import make_server
+
 
 host = "127.0.0.1"
 port = 8080