diff --git a/db/migrate/20170920022714_modify_position_type_for_challenge_choose.rb b/db/migrate/20170920022714_modify_position_type_for_challenge_choose.rb
new file mode 100644
index 000000000..94c1b6445
--- /dev/null
+++ b/db/migrate/20170920022714_modify_position_type_for_challenge_choose.rb
@@ -0,0 +1,8 @@
+class ModifyPositionTypeForChallengeChoose < ActiveRecord::Migration
+  def up
+    change_column :challenge_chooses, :position, :integer
+  end
+
+  def down
+  end
+end