A novel order processing in a shop side computer that carries out online sales of goods and the like is realized by this invention. In the shop side computer, upon receiving an order request from a customer terminal, content information of the customer order is registered, and an identification number of the customer order and a shop code are transmitted to a settlement system. Next, upon receiving the identification number of the customer order and an operation key from the settlement system, the content information of the customer order is read out according to the identification number of the customer order, and the content information of the customer order, the operation key, and the shop authentication information are transmitted to the settlement system. After that, upon receiving information indicating that the acceptance of the customer order is possible from the settlement system, information indicating the acceptance of the order is stored for the customer order. Then, at an arbitrary timing after the shipment of the commodity and the like relating to the customer order, the identification number of the customer order relating to an order price claim request is transmitted to the settlement system, and information indicating whether or not the order price claim processing succeeded is received from the settlement system.