In a norm setting section, a norm of an output voltage vector of an inverter is set based on a required torque and an electrical angle speed. In a phase setting section, a phase is set as controlled variables for performing a feedback control of an estimated torque to the required torque. In an operation signal generating section, operation signals are generated based on the norm set by the norm setting section and the phase set by the phase setting section, and the signals are outputted to the inverter. Based on the value of the phase, existence of abnormalities of a permanent magnet of a motor-generator is determined.