A user of devices (1) to (3) pays a predetermined accumulated fee to a device maker through a finance company every month. For each device of each user, a server (B) of the maker converts the sum of the accumulative fee into maintenance points and stores them in a point management table (6). After maintenance, the server (B) subtracts the points corresponding to the maintenance charge from the maintenance points to settle the maintenance cost. Service points are given according to an operation record sent from the devices (1) to (3) through a communications network (5) and a discount is given corresponding to the service points when the maintenance cost is settled.