A method is provided for easily avoiding undesirable effects on various physical values due to the change in temperature of a motor for driving a throttle valve without causing secondary problems. A technique is also provided for measuring the temperature of the motor electrically. The method uses a compensation device for correcting the power supply to the motor by detecting the impedance of the motor windings and/or the change in the motor temperature. The temperature of the motor is estimated from the current and voltage to the motor.