Abstract: A settlement relay system, which is connected to an affiliated shop terminal, a mobile communication terminal of a customer and a credit card company system, includes a communication part and a system control part. The communication part is connected to the affiliated shop terminal and the mobile communication terminal through a communication network. The system control part receives a settlement serial number data corresponding to a settlement from the mobile communication terminal via a communication network, receives a receipt serial number data from the affiliated shop terminal via a communication network, and performs a procedure corresponding to a transaction approval, when it is checked that the settlement serial number data and the receipt serial number data are matched with each other. Thus, a customer self settles through his/her own mobile communication terminal so that risk of duplication of the credit card may be prevented.