diff --git a/app/views/api/v1/users/memos/_memo.json.jbuilder b/app/views/api/v1/users/memos/_memo.json.jbuilder
index 26d94eef8..400dafc05 100644
--- a/app/views/api/v1/users/memos/_memo.json.jbuilder
+++ b/app/views/api/v1/users/memos/_memo.json.jbuilder
@@ -10,7 +10,7 @@ json.is_original memo.is_original
 json.memo_watched current_user.watched?(memo)
 # json.new_reply memo.new_reply
 json.praises_count memo.praises_count
-json.published_time memo.published_at.strftime("%Y-%m-%d %H:%M:%S")
+json.published_time memo.published_at&.strftime("%Y-%m-%d %H:%M:%S")
 json.replies_count memo.replies_count
 json.sticky memo.sticky
 json.subject memo.subject