PURPOSE: To enable the reduction of power consumption during starting by, after the detection of motor start-up, ceasing the following stepping processes.

CONSTITUTION: In a first stepping process, the output is produced by a stepping signal generator 3, and an energization switching circuit 4 is actuated, an output drive circuit 5 being turned on/off, according to control signals from a control circuit 2. Thus, stator coils u, v and w are sequentially excited. After the completion of the first stepping process, a first acceleration process is executed for a specified time with the final status of internal stepping maintained. If the control circuit 2 judges, during the process, that the motor has been completely started based on detect signals from a counter-electromotive force detecting circuit 7, connected to the stator coils u, v and w, the stepping process is ceased and the normal operation mode starts. If it is judged that the motor has not been sufficiently started, on the contrary, the counter-exciting current is sustained and a second stepping process starts. In the second stepping process, the direction of the current flow is reversed from negative to positive without quiescent times, and thus a large torque is obtained.