PROBLEM TO BE SOLVED : To easily and efficiently perform a process up to the conclusion of transaction contract in a real estate transaction method by which actual transaction is performed after accessing real estate information held by a real estate management mechanism through a communication network by using an information processing terminal and retrieving desired items of real estate.SOLUTION : The real estate management mechanism that constructs a real estate information database collectively acts a part as an intermediary business window up to a contract conclusion such as various consultations and transaction condition adjustment in response to a request from a customer. The real estate management mechanism also appropriately selects and designates a contract conclusion execution real estate agency other than a real estate agency handling a property concerned to request the contract conclusion execution real estate agency to make a contract in regard to the customer desire of a transaction contract conclusion.