diff --git a/app/models/book.rb b/app/models/book.rb
index 11368a6..5f8b929 100644
--- a/app/models/book.rb
+++ b/app/models/book.rb
@@ -75,7 +75,7 @@ class Book
       if (self.fields[t].type.to_s == "String" rescue false)
         fields_to_remove << t if (datas.where(t.to_sym.ne => nil).or(t.to_sym.ne => "").count == 0 rescue false)
       else
-        fields_to_remove << t if (datas.where(t.to_sym.ne => nil).count == 0 rescue false)
+        fields_to_remove << t if (datas.where(t.to_sym.ne => "").count == 0 rescue false)
       end
       pd_title <<  {
           "plugin_data_title" => I18n.t("personal_book.#{t}")