diff --git a/app/models/score.rb b/app/models/score.rb
index 86553f31..0e0df2fb 100644
--- a/app/models/score.rb
+++ b/app/models/score.rb
@@ -7,7 +7,7 @@ class Score < ApplicationRecord
   validates :composer,  length: { maximum: 255 }
   validates :arranger,  length: { maximum: 255 }
   # 最長でなく、数値の最大が5
-  validates :grade, allow_nil: true,
+  validates :grade, allow_blank: true,
                     numericality: { greater_than_or_equal_to: 0, less_than_or_equal_to: 5 }
   validates :m_time, allow_nil: true,
                      numericality: { only_integer: true, greater_than_or_equal_to: 0, less_than_or_equal_to: 1800 }