PURPOSE: To reduce the difference of static torque characteristic in between monophase and two-phase excitations, by changing the current value per phase in monophase and two-phase excitations.

CONSTITUTION: Each exciting phase 1∼4 is constituted so that either high driving voltage VH or low driving voltage VL may be impressed through change-over switches S 1 and S 2. A stepping motor is controlled by changing over the voltage so that the high driving voltage VH may be impressed when the driving exciting phase is in monophase excitation while the low driving voltage VL may be impressed when the driving exciting phase is in two-phase excitation. In this way, the total driving current in the monophase and two-phase excitations can be levelled, so that either of the monophase exciting or two- phase exciting state can be obtained which is basically equal static torque characteristic.