PURPOSE : A system for a real estate consultant mediating a seller and a buyer on the Internet and a method for mediating the system are provided to perform a reliable contract at an on-line environment by performing a chatting process among a seller, a buyer, and a consultant on the Internet.CONSTITUTION : A consultant server(30) has a site URL(Uniform resource locators) for managing a homepage on the Internet and constructs a multiple program for progressing each wanted operation additionally when the site URL is connected using a plurality of sellers computers(10) and buyers computers(20). Elements of the consultant server(30) are described as follows. A selling article information managing module manages and supplies information about real estate selling articles. A chatting window displaying module is provided for a chatting among a seller, a buyer, and a consultant. A selling article information database includes sellers and information of the corresponding consultant. A control unit controls a chatting process. A GIS database includes a GIS image with respect to a predetermined area. A GIS module manages and supplies the GIS image.? KIPO 2002