Pseudonymous id management apparatus and its method, pseudonymous id management system and service offering method using the same

PURPOSE: A pseudonymous ID management apparatus and a method thereof, and pseudonymous ID management system and service offering method using the same are provided to reduce the damage resulting from the leakage of a personal ID by reissuing a social ID number according to necessity. CONSTITUTION: An anonymous client terminal(100) includes a client program, and accesses an anonymous ID management device(200) through a wired/wireless communication network(600). An authentication device(300) includes a sever for authenticating a user based on a user identifier. A web service device(400) includes a server providing a web service to a user, and an offline reception terminal(500) is a terminal for inputting reception information.