diff --git a/app/models/graduation_work.rb b/app/models/graduation_work.rb
index 96dce0c49..7fb0ecc24 100644
--- a/app/models/graduation_work.rb
+++ b/app/models/graduation_work.rb
@@ -55,7 +55,7 @@ class GraduationWork < ApplicationRecord
   end
 
   def delete_atta atta
-    last_score = graduation_work_scores.where.not(score: nil).last
+    last_score = graduation_work_scores.last
     (atta.author_id == User.current.id) && (last_score.blank? || last_score.try(:created_at) < atta.created_on)
   end
 
diff --git a/app/views/student_works/show.json.jbuilder b/app/views/student_works/show.json.jbuilder
index 7b3a91b5e..8cb3ee7ca 100644
--- a/app/views/student_works/show.json.jbuilder
+++ b/app/views/student_works/show.json.jbuilder
@@ -11,7 +11,7 @@ json.update_user_name @is_evaluation ? "匿名" : @work.update_user.try(:real_na
 json.update_atta @homework.late_duration && @is_author
 
 json.attachments @attachments do |atta|
-  json.partial! "attachments/attachment_simple", locals: {attachment: atta, delete: false, }
+  json.partial! "attachments/attachment_simple", locals: {attachment: atta, delete: false }
 end
 
 unless @is_evaluation