According to one aspect of the present invention for accomplishing the aforementioned purpose, a mobile authentication method performed by a portable user device comprises the steps of extracting a telephone number of the portable user device, transmitting member information including the telephone number to an authentication server, receiving a user authentication number using the member information from the authentication server, extracting unique user identifiers (UUID) of an application (app) installed in the portable user device, and transmitting the extracted UUID of the app and the received user authentication number to a service server.