diff --git a/db/migrate/20190713022300_modify_md_attachment_url_for_md_cotents.rb b/db/migrate/20190713022300_modify_md_attachment_url_for_md_cotents.rb
index 99ea12309..10b821fc5 100644
--- a/db/migrate/20190713022300_modify_md_attachment_url_for_md_cotents.rb
+++ b/db/migrate/20190713022300_modify_md_attachment_url_for_md_cotents.rb
@@ -29,7 +29,7 @@ class ModifyMdAttachmentUrlForMdCotents < ActiveRecord::Migration[5.2]
 
     plats = PlatformSample.where(samples_type: ['introduction', 'knowledge'])
     plats.find_each do |p|
-      p.update_column(:contents, p.contents.gsub("![](/attachments/download", "![](/api/attachments")) if p.introduction.present?
+      p.update_column(:contents, p.contents.gsub("![](/attachments/download", "![](/api/attachments")) if p.contents.present?
     end
   end
 end