An inverter is provided with a temperature sensor for detecting the temperature of the inverter. A plurality of threshold values are set up for the temperature detected by the temperature sensor, electric current restricting conditions different from each other are set up for each of the temperature regions sorted out by each threshold value, and an inverter restricting unit for applying a restriction to an electric current command applied to the inverter in dependence on the electric current restricting condition of the temperature region, in which the detected temperature is included. Without the drivability of an automobile being disturbed, by means of a temperature control of the inverter, not only are any change in characteristic and impairment, resulting from an overheating thereof, prevented, but also an undesirable reduction of the life of the inverter is avoided.