PROBLEM TO BE SOLVED : To collectively perform the business management of building estate.SOLUTION : This real estate business management system is provided with a storage device 13 storing predetermined business management information, a computer 11 connected to the storage device for judging whether or not to receive an application and an input/output device 12 connected to the computer. When one of plural business management methods is selected as a selected business management method, the computer judges whether or not a building condition stipulated by the application supplied from the input/output device is suited to the selected business management method on the basis of the business management information.