PURPOSE: To increase the reliability of the system of control circuit by a method wherein second control means, controlling the supply and interruption of an operating electric source for first control means, is provided to prevent the breakage of a circuit element in an inverter control unit by an abnormal signal when the control operation of the inverter control unit is stopped.

CONSTITUTION: The circuit is constituted so that an outdoor machine main switch 21 is opened and the control operation of the inverter control unit 23 is stopped temporarily by the first control means 8, the inverter control unit 23 is operated by the first control means 8 for a period from the time when the temporary stopping period has been elapsed to the time when the charged charge of a smoothing capacitor C has been discharged at least through the operating inverter control unit 23, and the operating electric source of the first control means is interrupted by the second control means 9 after the period has been elapsed. Therefore, the operation of the inverter control unit is finished after the charged charge of the smoothing capacitor C has been discharged and, thereafter, the electric source of the first control means 8 such as a micro-computer or the like may be interrupted.