PURPOSE: To rotatably drive a two-phase DC brushless motor in a high efficiency by selectively switching a one-phase operation and a two-phase operation of driving coils of the motor and executing the two-phase operation for a predetermined time at the time of starting the motor.

CONSTITUTION: When a signal of a high level is input to a control terminal T1, a transistor Q6 is turned ON, a transistor Q5 is turned OFF, and a two- phase operation of driving coils L1, L2 by transistors Q1, Q2 is conducted. Then, when a signal of a low level is input, the transistor Q6 is turned OFF, but a voltage is applied from a power source terminal Tv, and the transistor Q5 is turned ON, the Q2 is turned OFF, and a current to the coil L is stopped. Accordingly, the one-phase operation is conducted only when the signal is the high in level. Further, when the power source is turned ON in the case of starting it, a time constant voltage is gradually raised, and after it reaches a divided voltage, a transistor Q3 is turned ON, and the transistor Q3 is turned OFF during a time determined according to the time constant, and the two-phase operation is executed.