One or more multiphase power converters are connected to a power supply via a high potential line and a low potential line, convert DC power of the power supply into multiphase alternate current power by operations of inverter switching elements, and apply a voltage to each of phase windings of the multiphase winding set. A DC rotating machine switch are made up of two or more legs, each of which is made up of switches on a high potential side and a low potential side connected in series via a DC motor terminal connected to a second terminal that is an end of the DC rotating machine. The DC rotating machine switch makes a voltage of the DC motor terminal variable by switching. A control unit controls operations of the inverter switching elements and the DC rotating machine switch.