diff --git a/linebot_app.py b/linebot_app.py
index d9be596..0a7082a 100755
--- a/linebot_app.py
+++ b/linebot_app.py
@@ -125,7 +125,7 @@ def message_text(event):
                 messages=[TextMessage(text=answer)]
             ))
 
-    log_file.write("bot_answer: " + answer + "\n")
+    log_file.write(", bot_answer: " + answer + "\n")
     log_file.close()
 
 #    with ApiClient(configuration) as api_client: