An online shopping system is provided for minimizing transportation costs by using a plurality of prestandardized delivery containers to eliminate waste in product delivery, and enhancing the convenience of users by automatically selecting a delivery container in accordance with the size of a selected product and clearly denoting information about an order closing time, a delivery source location, etc. When the user inputs the type and the quantity of a product, a delivery container which is optimal for storing the ordered product is automatically selected based on the volume of the product and an internal capacity of the delivery container, and a price of the selected delivery container is displayed. Thereafter, each time an additional product is ordered, a new delivery container which is optimal for storing all ordered products including the additional product is selected, and a price of the new delivery container is calculated. Information related to a price difference between a previously selected delivery container and the newly selected delivery container selected is obtained and presented to the user in accordance with prescribed display methods.