An air conditioner includes an outdoor device and an indoor device. The outdoor device includes an outdoor control unit that is operated at the voltage of a smoothing capacitor; a power-supply switching relay to which a signal line is connected; an inrush-current preventing-relay drive unit that is operated when single-phase AC power is supplied between a power-signal common line and the signal line via an outdoor activation relay in the indoor device and the power-supply switching relay; a first inrush-current preventing relay that is connected in parallel with a power supply relay and is controlled by the inrush-current preventing-relay drive unit; and a second inrush-current preventing relay that is connected in parallel with the first inrush-current preventing relay and is controlled by the outdoor control unit. The outdoor control unit closes the second inrush-current preventing relay when the external power supply is interrupted.