To store a detected commodity code, a quantity, etc., as purchase information in a purchase information memory by storing the number of a shopping card and commodity information while a customer is selecting commodities to be purchased, detecting the commodity code, and calculating the detected commodity code, quantity, etc.

The customer starts selecting commodities by pressing an OK button. At the same time, a calculation result is added and stored as purchase information in a purchase information memory 24. After purchasing operation, the customer moves the shopping card to a place where a communication with a commodity liquidation terminal is possible. When a clerk presses the payment liquidation button of the commodity liquidation terminal, a card terminal 8 sends a liquidation start command out and also sends the purchase information stored in the purchase information memory 24, the cart number in a cart number memory 25, and card data, etc., when the customer's shopping card is inserted into a card input/output part 22 to the commodity liquidation terminal at a time.