To always maintain the amount of a refrigerant flowing into room heat exchangers at a proper level regardless of the number of the room heat exchangers to be operated.

A multi-airconditioner is provided with a compressor 112 for compressing a refrigerant, an outdoor heat exchanger 120 into which flows a refrigerant discharged from the compressor 112 and a number of room heat exchangers 152a and 152b which is linked in parallel to the outdoor heat exchanger 120 to let the refrigerant flow thereinto. When any one alone of the room heat exchangers 152a and 152b is operated, a bypass part 164 makes a part of the refrigerant from the outdoor heat exchanger 120 bypass to the compressor 112 to maintain the amount of the refrigerant flowing into the room heat exchangers 152a and 152b at a proper level. This can prevent phenomenon of freezing of the refrigerant flowing in excessive quantities into the room heat exchangers 152a and 152b and inflow of a liquid refrigerant yet to be evaporated sufficiently into the compressor 112 thereby achieving a higher reliability of the compressor 112.