A central air-conditioning system conditions a house having a plurality of rooms. When a person is not present in any of the rooms, each room is conditioned in energy-saving conditioning mode having a low load. On the other hand, when the person is detected in any of the rooms, a controller switches an operating mode for conditioning the room, in which the person is detected, from the energy-saving conditioning to rapid conditioning. Air-conditioner ducts respectively connected to the remaining rooms are closed. Therefore, cold air or warm air from an air-conditioning unit is supplied to the room in which the person is detected, while the cold air or warm air is not supplied to the rooms in which the person is not present. As a result, the room that has been switched from energy-saving conditioning to rapid conditioning is conditioned in a concentrated manner.