PURPOSE : A system for concluding a real estate transaction is provided to enhance a reliability by preventing a generation of various kinds of disputes in advance when a real estate contract is concluded through the Internet.CONSTITUTION : A real estate relay server(100) analyzes transaction contents of a real estate, prepares a written contract, and downloads the prepared written contract to contractor terminals(200, 300). The real estate relay server(100) requests the contractor to input an authentication sign(identifier, password, fingerprint), and codes the inputted information using a public key of a notarial server(400). The notarial server(400) decodes the coded contract information using its password key, notarizes detected contract information, and stores the contract information and the notarized information. If a contractor requests the contract information, the notarial server(400) detects the contract information and the notarized information, codes the information using a public key of the real estate relay server(100), and transmits the information to the real estate relay server(100). The real estate relay server(100) decodes the coded contract information using its password key. The real estate relay server(100) codes the contract information and the notarized information using a public key of the contractor terminals(200, 300), and transmits the information to the contractor terminals(200, 300), respectively.? KIPO 2003