PROBLEM TO BE SOLVED : To provide sales information of a real estate and automatically determine application competence of a purchaser by using a public communication network and to speed up work until negotiation rights ascertainment of a pre-contract stage.SOLUTION : The system is provided with a seller side information processor advertising real estate sales and receiving purchase applications, a plurality of purchaser side information processors provided in purchaser side terminals to carry out purchase applications, and the public communication network connecting all the information processors by an open network. It is provided with an information providing means providing real estate detailed information and invitation information, a personal information inputting means for inputting personal information of the purchaser, a competence determining means determining competence per purchaser on the basis of the personal information, a registering means registering a purchaser having competence by an individual registration number, a registration check means determining a registration application from a purchaser on the basis of the personal information of an individual purchaser to prevent double registration and registration of a same household family name, a purchase applying means for carrying out a purchase application for a specific real estate by the registration number, and a competition calculating means sequentially calculating application competition by tabulating application results per individual real estate from individual purchasers.