PURPOSE: To reduce vibration, heat and noise generated in a pulse motor substantially by shortening a conducting time of driving pulse at a low-speed rotation.

CONSTITUTION: When a control circuit 1 judges that a space control speed is slower than a prescribed one, said circuit accesses a timer controller 11 within a control signal generator 10 together with a timer controller 3 within a driving pulse generator 2. A timer signal outputted from the driving pulse generator 2 becomes a rotational pulse with excitation phases A-D via a counter 6 and a logic 7 and is sent to a driving pulse controller 20. On the other hand, the timer controller 11 receives an output signal of the counter 6, accesses a timer value data table 12 on the basis of said output signal, reads out timer data stored in said table, controls the gate-ON time of gates 21-24 corresponding to the excitation phases A-D via a logic circuit 13 and shortens a conducting time of driving pulse.