PROBLEM TO BE SOLVED : To provide a real estate buying/selling or lease transaction method using a communication network capable of enhancing the reliability of real estate information concerning property for which the buying/selling or lease of a real estate is desired that is inputted from a terminal by a seller or a lender.SOLUTION : This real estate buying/selling or lease transaction method comprises a real estate storage process 100 for connecting terminal equipment at a seller and lender side through a communication network to a storage device and for making a computer store and register real estate information concerning a property are buying/ selling or lease of which is desired and which is inputted from the terminal by the seller and lender, and a real estate information confirmation process 200 for making an operator confirm the stored and registered real estate information of the seller or the lender and for correcting the real estate information which is unclear, insufficient, or incorrect. Thus, it is possible to collect the real estate information the reliability or accuracy of which is higher than conventional real estate information registered only at the seller and lender side and to construct a data base whose information is very reliable.