PURPOSE: To satisfactorily and effectually utilize redundant capability when there is produced a redundant capability of an outdoor machine.

CONSTITUTION: There are provided an outdoor machine 1, a plurality of indoor machines A, B, C, D connected to the outdoor machine 1 and installed in a plurality of rooms, and a control unit 40. The control unit 40 groups the indoor machines A, B, C, D into the main indoor machines A, B, C and the auxiliary indoor machine D, and precidently provides capability of the outdoor machine 1 to the operation of the main indoor machines A, B, C, and as loads of the main indoor machines A, B, C are reduced, the control unit provides a redundant fraction of the main indoor machines A, B, C to the operation of the auxiliary indoor machine D.