Index: branches/version-2_12-dev/html/js/products.js
===================================================================
--- branches/version-2_12-dev/html/js/products.js	(revision 21893)
+++ branches/version-2_12-dev/html/js/products.js	(revision 21895)
@@ -10,5 +10,5 @@
 
                       // 規格1のみの場合
-                      if ($sele2.val() == undefined) {
+                      if (!$sele2.length) {
                           checkStock($form, product_id, $sele1.val(), '0');
                       }