PROBLEM TO BE SOLVED : To suppress an initial cost required when leasing an office space as low as possible.SOLUTION : Information on a customer' s desire for leasing real estate and equipment is received, and information on real estate and furniture is memorized together with the guarantee money for the real estate. A lease fee obtained by leveling the guarantee money is computed and outputted so as to inform the customer of it. The lease fee computed this way is collected from the customer, and the lease fee collected is paid to the owner of the real estate.