A credit card transaction system that is used for contracts for various electronic-commerce services comprises a mobile station 100, a mobile telephone network 20, a mobile packet communication network 30, a CAT 40a, 40b, . . . , a CAFIS network 50, a credit card company's server 60A, 60B, . . . , and the Internet 70. A request from the mobile station 100 for a credit card contract is transmitted to any one of the credit card company's server 60A, 60B, . . . through a gateway server 32; in a case where the contract is approved, credit card contract information is transmitted from any one of credit card company's server 60A, 60B, . . . to the mobile station 100 through the gateway server 32, the credit card contract information being stored in the mobile station 100.