diff --git a/python_tests/test_boto3_artifact.py b/python_tests/test_boto3_artifact.py
index cafb9f91..0030c07a 100644
--- a/python_tests/test_boto3_artifact.py
+++ b/python_tests/test_boto3_artifact.py
@@ -9,23 +9,28 @@ from optuna_dashboard.artifact.boto3 import Boto3Backend
 @mock_s3
 class Boto3BackendTestCase(TestCase):
     def setUp(self) -> None:
-        self.s3_client = boto3.resource("s3")
-        self.bucket = self.s3_client.create_bucket(Bucket="moto-bucket")
+        self.s3_client = boto3.client("s3")
+        self.bucket_name = "moto-bucket"
+        self.s3_client.create_bucket(Bucket=self.bucket_name)
 
     def tearDown(self) -> None:
-        self.bucket.objects.all().delete()
-        self.bucket.delete()
+        objects = self.s3_client.list_objects(Bucket=self.bucket_name).get("Contents", [])
+        if objects:
+            self.s3_client.delete_objects(Bucket=self.bucket_name, Delete={
+                "Objects": [{"Key": obj["Key"] for obj in objects}],
+                "Quiet": True
+            })
+        self.s3_client.delete_bucket(Bucket=self.bucket_name)
 
     def test_upload_download(self) -> None:
         artifact_id = "dummy-uuid"
         dummy_content = b"Hello World"
 
-        backend = Boto3Backend(self.bucket.name)
+        backend = Boto3Backend(self.bucket_name)
         backend.write(artifact_id, io.BytesIO(dummy_content))
-
-        objects = [obj for obj in self.bucket.objects.all() if obj.key == artifact_id]
-        assert len(objects) == 1
-        assert objects[0].get()["Body"].read() == dummy_content
+        assert len(self.s3_client.list_objects(Bucket=self.bucket_name)['Contents']) == 1
+        obj = self.s3_client.get_object(Bucket=self.bucket_name, Key=artifact_id)
+        assert obj["Body"].read() == dummy_content
 
         with backend.open(artifact_id) as f:
             actual = f.read()
@@ -33,9 +38,11 @@ class Boto3BackendTestCase(TestCase):
 
     def test_remove(self) -> None:
         artifact_id = "dummy-uuid"
-        backend = Boto3Backend(self.bucket.name)
+        backend = Boto3Backend(self.bucket_name)
         backend.write(artifact_id, io.BytesIO(b"Hello"))
-        assert len([obj for obj in self.bucket.objects.all() if obj.key == artifact_id]) == 1
+        objects = self.s3_client.list_objects(Bucket=self.bucket_name)['Contents']
+        assert len([obj for obj in objects if obj["Key"] == artifact_id]) == 1
 
         backend.remove(artifact_id)
-        assert len([obj for obj in self.bucket.objects.all() if obj.key == artifact_id]) == 0
+        objects = self.s3_client.list_objects(Bucket=self.bucket_name).get('Contents', [])
+        assert len([obj for obj in objects if obj["Key"] == artifact_id]) == 0