PURPOSE: To reduce the temperature rise of a motor by providing the exciting phase of each step with an OFF section at the time of a low speed rotation, when a stepping motor is rotated by successively switching the driving pulse of a stator coil with plural phases.

CONSTITUTION: When a driving pulse 10a is inputted to an excitation control circuit 8a, respective a pair of poles out of poles 11-14 of the stator of a stepping motor 9 are successively excited by exciting waveforms Q11-Q14. When e.g. the poles 11 and 12 become S poles, a rotor R steps to the midway between said poles 11 and 12 and stops as shown in the drawing. Then, when poles 12 and 13 are excited, said rotor R steps 90° and stops at the position indicated by the dotted line. At the time of a low speed rotation, power application to poles to be excited is limited to the beginning and terminal parts of an exciting waveform and no power is applied during the intermediate periods. Thus, it is possible to inhibit the temperature rise of a coil and to reduce the amount of power consumption.