PURPOSE: To always stabilize rotational driving by securing necessary torque with respect to voltage change by successively detecting the voltage applied to a pulse motor and altering a phase exciting time so as to ensure necessary torque on the basis of the detected value.

CONSTITUTION: When the start control of a pulse motor 5 is started, voltage is detected by an A/D converter 9 and the acceleration table corresponding to the detected value is selected from a plurality of acceleration tables to perform the control of acceleration. At the time of the constant speed control of the pulse motor 5 after the control of acceleration is completed, voltage is detected by the A/D converter 9 at each time when the phase excitation changeover of the pulse motor 5 is performed once or a plurality of times and constant speed control is performed using the value of a phase exciting time corresponding to the detected value from the acceleration table. When the stop control of the pulse motor 5 is started after acceleration control is completed, voltage is detected by the A/D converter 9 and a deceleration table corresponding to the detected value is selected from a plurality of deceleration tables to perform deceleration control.