Index: branches/version-2_13-dev/data/Smarty/templates/admin/products/product.tpl
===================================================================
--- branches/version-2_13-dev/data/Smarty/templates/admin/products/product.tpl	(revision 23546)
+++ branches/version-2_13-dev/data/Smarty/templates/admin/products/product.tpl	(revision 23575)
@@ -39,7 +39,7 @@
         var selectedOptions = <!--{$tpl_json_category_id}-->;
         $('#' + select + ' option').attr('selected', false);
-        for(var i=0; i<selectedOptions.length; i++){
+        for(var i=0; i < selectedOptions.length; i++){
             $('#' + select + ' option[value="' + selectedOptions[i] + '"]')
-                .attr('selected', 'selected');
+                .prop('selected', 'selected');
         }
     }
@@ -66,5 +66,5 @@
     // target の子要素を選択状態にする
     function selectAll(target) {
-        $('#' + target).children().attr({selected: true});
+        $('#' + target).children().prop('selected', 'selected');
     }