PURPOSE: To provide an outdoor unit for a multizone air conditioner which has a long life and places a plurality of compressors.

CONSTITUTION: One inverter 2 having power supply capacity of one compressor is provided in an outdoor unit 1 for a multizone air conditioner which places a plurality of compressors 6. The compressors 6 employ the inverter compressors, and a switching circuit 3 for connecting one of the compressors to an inverter power supply and connecting the remaining compressors to a commercial power supply is provided. Accordingly, the circuit 3 has the operating time integrator 4 of the compressors 6 to connect the compressor in which the integrated time of the integrator 4 at the time of starting the compressors 6 is minimum to the inverter power supply and the other compressors are switched by the circuit to be connected to the commercial power supply.