PURPOSE: To shorten a seek completion time by blocking a motor-driving current flowing through another path at the time of a reduction control through separately providing emitter circuits of a pair of transistors for switching the current direction of a voice coil so as to block a reverse current to the power supply side.

CONSTITUTION: Emitter circuits 100, 200 of transistors Q11 and Q21 are provided separately to the plus power supply side. Even if a voltage by the counter- electromotive force of a terminal 14 is higher than a supply voltage plus Vcc on the plus side, a driving current flowing to a voice coil 10 through a reverse flow element by a diode D6 is not shunted to the plus power supply line side but all said driving current flowing through said voice coil 10 flows to a current- sensing resistor RS1 via transistor Q12 as shown by a solid line A in the drawing. Therefore, the driving current flowing through the voice coil 10 can be detected accurately by said current-sensing resistor RS1 also in a reduction control at the time of a seek completion.