diff --git a/ecs/jskult-webapp/src/aws/s3.py b/ecs/jskult-webapp/src/aws/s3.py
index de11949c..2b6251b1 100644
--- a/ecs/jskult-webapp/src/aws/s3.py
+++ b/ecs/jskult-webapp/src/aws/s3.py
@@ -23,7 +23,7 @@ class S3Client(AWSAPIClient):
                 'Bucket': bucket_name,
                 'Key': file_key,
                 # 別ファイル名に変更するための仕掛け。Unicode文字はquoteでエスケープが必要
-                'ResponseContentDisposition': f'attachment; filename="{quote(download_filename)}"'
+                'ResponseContentDisposition': f"attachment; filename*=UTF-8''{quote(download_filename)}"
             },
             # 有効期限20分
             ExpiresIn=1200