A control unit controls driving of a motor by controlling a first inverter unit and a second inverter unit, specifically by controlling on/off operations of FETs. The control unit functions as an abnormality detection device. The control unit detects a short-circuit abnormality between a first winding set and a second winding set or between the first inverter unit and the second inverter unit, before starting to control driving of the motor, based on phase current values detected by current detectors when a high-side FET of the first inverter unit and a low-side FET of the second inverter unit are turned on.