Index: branches/version-2_5-dev/data/class/pages/products/LC_Page_Products_List.php
===================================================================
--- branches/version-2_5-dev/data/class/pages/products/LC_Page_Products_List.php	(revision 19943)
+++ branches/version-2_5-dev/data/class/pages/products/LC_Page_Products_List.php	(revision 19944)
@@ -166,4 +166,8 @@
                 $objCartSess = new SC_CartSession();
                 $objCartSess->addProduct($product_class_id, $this->arrForm['quantity'], $product_type);
+
+                // カート「戻るボタン」用に保持
+                $_SESSION['cart_referer_url'] = $_SERVER['HTTP_REFERER'];
+
                 SC_Response_Ex::sendRedirect(CART_URLPATH);
                 exit;
Index: branches/version-2_5-dev/data/class/pages/products/LC_Page_Products_Detail.php
===================================================================
--- branches/version-2_5-dev/data/class/pages/products/LC_Page_Products_Detail.php	(revision 19943)
+++ branches/version-2_5-dev/data/class/pages/products/LC_Page_Products_Detail.php	(revision 19944)
@@ -197,4 +197,7 @@
                     $objCartSess->addProduct($product_class_id, $this->objFormParam->getValue('quantity'), $product_type);
 
+                    // カート「戻るボタン」用に保持
+                    $_SESSION['cart_referer_url'] = $_SERVER['HTTP_REFERER'];
+
                     if (!empty($_POST['gmo_oneclick'])) {
                         $objSiteSess = new SC_SiteSession;
Index: branches/version-2_5-dev/data/class/pages/cart/LC_Page_Cart.php
===================================================================
--- branches/version-2_5-dev/data/class/pages/cart/LC_Page_Cart.php	(revision 19908)
+++ branches/version-2_5-dev/data/class/pages/cart/LC_Page_Cart.php	(revision 19944)
@@ -189,5 +189,18 @@
 
         // 前頁のURLを取得
-        $this->tpl_prev_url = $objCartSess->getPrevURL();
+        // TODO: SC_CartSession::setPrevURL()利用不可。
+        if (!preg_match("/cart/", $_SERVER['HTTP_REFERER'])) {
+            if (!empty($_SESSION['cart_referer_url'])) {
+                $_SESSION['cart_prev_url'] = $_SESSION['cart_referer_url'];
+                unset($_SESSION['cart_referer_url']);
+            } else {
+                if (preg_match("/entry/", $_SERVER['HTTP_REFERER'])) {
+                    $_SESSION['cart_prev_url'] = URL_PATH . 'entry/kiyaku.php';
+                } else {
+                    $_SESSION['cart_prev_url'] = $_SERVER['HTTP_REFERER'];
+                }
+            }
+        }
+        $this->tpl_prev_url = $_SESSION['cart_prev_url'];
     }