The present invention is a user authentication method using a UICC-ID of the mobile terminal, and as an invention of the electronic transaction method and system for issuing and using electronic cash, vouchers, coupons and so on using the same issuer issuing an electronic coupon server and the user's personal by constructing in between the carrier server that provides the authentication information includes a relay center, which facilitates the configuration of the electronic transaction system, which may have a transaction information at the relay center transmits the transaction information by the user when the electronic transaction generating a wireless communications network , it gives the electronic trading system that allows users to connect to the Web Center system of transit can check your transaction history. Becomes present by the present issuer is linked between the server and the carrier server facilitated by simplifying the construction of the electronic trading system, by using the SIM or USIM and ID (e.g. UICC-ID) information of a general-purpose IC card, such as in a user's mobile communication terminal by performing a user authentication and transaction procedure easier the user's authentication, and it is possible to manage independently a transaction information in memory of the mobile communication device can improve the efficiency of use of an electronic transaction.