PROBLEM TO BE SOLVED : To cultivate a potential purchaser who presently uses leased premises exclusively and have plans to purchase them since it is anticipated that the number of purchase/sales transactions of real estate properties further decreases due to an increase of premises in stock and an increase of the number of vacant rooms of leased premises resulting from an oversupply of real estate properties.SOLUTION : A real estate purchase/sale promotion organization 1 purchases an object real estate property 3 from a real estate property owner 2. Then a server 1A provides an offer advertisement through Internet communication while requesting a real estate broker 4 to make an offer. The real estate purchase/sale promotion organization 1 makes a lease contract with the purchase option with a tenant 5 through the real estate broker 4 or a tenant 5 who has applied to the server 1A through Internet communication. When the tenant holding the option to purchase the leased real estate property 3 over a certain period of time executes the purchase option, the real estate purchase/sale promotion organization 1 makes a discount according to the period when the tenant 5 has leased the real estate property, and the sum of the paid rent, and sells it at a low price.COPYRIGHT : (C)2010, JPO&INPIT