To restrain heat generation of a motor by decreasing ripple current without making a control circuit complicated.

At the time of high speed rotation, a stepping motor 1 is driven by a normal exciting system, and at low speed rotation, the motor 1 is driven by a micro-stepping system. A decrease in current during OFF at the time of chopping operation for constant current to be supplied during micro-stepping driving is made by the combination of high speed damping and low speed damping, and even at the low speed rotation, the rotator core 7 of the motor 1 is rotated smoothly to minimize vibration.