PURPOSE : A method and a device for intermediating real estate transaction based on network are provided to predict that real estate will be converted into cash by advance contract conclusion. This invention maintains objectivity of real estate price by proper price fixed in real estate market. Therefore, transaction of real estate can be activated, and stock concept of real estate can be introduced.CONSTITUTION : If a user transmits a connection requesting signal to a web server(201), the web server transmits a homepage to the user(203). If user transmits the connection requesting signal to a wap server through a mobile communication terminal device, the web server connected to the wap server transmits data correspondent to the connection requesting signal to the user through the wap server. Communication with the user can be executed with wireless mobile communication or wireless beeper communication. The web server determines if the user is a member by receiving user ID and password(205). If the user is not a member, the web server transmits a network document for member registration to the user. The user inputs input items in the network document, and transmits the network document. Then, the web server stores the transmitted network document in a user managing database. By these processes, the user can be authenticated. The user managing database stores member ID, password, name, sex, address, telephone number, e-mail address, job and so on. The user requests sale or purchase(211).? KIPO 2002