When a processor sets a current instruction value and a rotating direction of a motor, two analog instruction signals of a positive polarity and a negative polarity are obtained after completion of a D/A conversion, the analog instruction signal of the negative polarity is selected by an instruction in the CW direction, and the analog instruction signal of the positive polarity is selected by the instruction in the CCW direction. The analog instruction signal of the polarity selected is added to a motor current detection signal which was negatively fed back by an adding circuit, so that an analog deviation signal is derived. A pulse width modulating circuit section outputs a PWM pulse in the CW direction for the negative polarity of the analog deviation signal and outputs a PWM pulse in the CCW direction for the positive polarity. At the same time, a CW switching signal is outputted for the negative polarity of the analog deviation signal and a CCW direction switching signal is outputted for the positive polarity. By inverting a detection signal of current detecting resistors serially connected to the motor, a negative feedback is certainly performed.