PURPOSE: To narrow the hysteresis width so as to improve the stopping position accuracy of a motor actuator by switching the drive of a DC servo motor to PWM drive from DC drive when the detected rotational position value of the servo motor becomes closer to a target stopping position of the servo motor.

CONSTITUTION: When a control switch is pressed, a CPU 4 applies a DC voltage across a DC servo motor 1 by driving a driver 5. Since a DC voltage VCC is applied across a potentiometer 3, the output voltage of the variable terminal of the potentiometer 3 changes as the motor 1 rotates. The CPU 4 always fetches the output voltage of the variable terminal through an input protection circuit 6 as a present position signal. When the CPU 4 judges that the present position signal becomes closer to a target position, the CPU 5 commands the driver 5 to switch the voltage applied across the motor 1 to a PWM voltage from the DC voltage. Therefore, the rotating speed of the motor 1 becomes slower and the stopping position accuracy of a motor actuator 2 can be improved by narrowing the hysteresis width.