PURPOSE: To drive with a constant current without always feeding back a current by so deciding a correction amount of pulse generating means that a real current flowing to an H bridge becomes equal to a specific target current.

CONSTITUTION: A stepping motor 10 has two coils of an A-phase coil 12 and a B-phase coil 13 for driving a rotor 1, and currents flowing to the coils are controlled by first and second H bridges 21, 22. Power is supplied from a power source bus 60 to the bridges 21 and 22 through a current detecting resistor 50. Specific target currents flows to phases of the motor 10 in a specific operating state immediately after the power source is turned ON, a correction coefficient is calculated based on a deviation from a real current to be detected by the resistor 50, and the bridge is driven by an open loop control using the coefficient in a normal operating state. As a result, a constant current drive can be always performed without feeding back.