PURPOSE : An online real estate authentication and auction system and method is provided to authenticate a real estate, an ownership or a payment by an online information processing step so that it can enhance a safety and a reliability in transacting real estates.CONSTITUTION : The system comprises a real estate registration & auction management module(80), a real estate authentication module(50), an ownership authentication module(60), and a payment authentication module(40). The real estate registration & auction management module(80) receives a registration request of real estates to be sold from a seller' s terminal, stores the request at a database, and performs an auction on the registered real estates. The real estate authentication module(50) and the ownership authentication module(60) receive real estate authentication and ownership authentication informations from certification authorities, and opens the informations to real estate buyers. The payment authentication module(40) makes an auction winner deposit corresponding money at a specific account, and remit money to a real estate seller' s account if the ownership is transferred.? KIPO 2002