diff --git a/app/models/bulletin.rb b/app/models/bulletin.rb
index b173c2c..8d4e338 100644
--- a/app/models/bulletin.rb
+++ b/app/models/bulletin.rb
@@ -107,7 +107,9 @@ class Bulletin
   before_create :set_expire
   before_save :check_limit
   before_save do
-    @is_hidden_changed = self.is_hidden_changed?
+    if @is_hidden_changed.nil? || @is_hidden_changed != true
+      @is_hidden_changed = self.is_hidden_changed?
+    end
     if self.is_top_changed? && !self.is_top
       self.sort_number = nil
     end