PURPOSE : An online real estate auction system for small investors and service method thereof are provided to randomly establish the size of investment according to the economical ability of the small investors by developing joint investment products for the small investors.CONSTITUTION : A small investor server(2) accesses to an auction service operator server(1) in online. The small investor server receives information for auction articles. The small investor server applies for investment of the auction articles selected through the information. A guarantee institution server(3) transmits an online certificate to a winning small investor server. An auction information providing server(4) provides real time auction information.COPYRIGHT KIPO 2012