PURPOSE: To prevent a step-out in a stepping motor for driving an imaging unit for a copying machine or the like.

CONSTITUTION: The first driving circuit system is constituted of counters 2, 3, and the second driving circuit system is constituted of counters 4, 5. A CPU1 first gives dividing ratio of the first step and a pulse count number to the first driving circuit system and dividing ratio of the second step and a pulse count number to the second driving circuit system. First the output of the first driving circuit system is supplied to a motor driver and the output of the second driving circuit system is supplied to the motor driver when an interruption signal from the first driving circuit system is generated. At this time dividing ratio of the third step and a pulse count number is repeatedly given to the first driving circuit system.