To provide a real estate transaction method, a real estate information registration method, and a system capable of obtaining a fresh, abundant and safe property information reading site allowing the conclusion of a mediation contract related to the trade of a real estate property on a network, having no unnecessary information in readable property information.

In this system, a consumer can retrieve a trader member on the network and select a desired trader member to conclude the mediation contract. In the retrieval of the trader member, a trader fit for various conditions can be selected. Because newly generated/collected property information is collated with property data already registered in a property DB, overlap data are not registered. Partially coinciding data are registered as history information.