PURPOSE: To strengthen holding force at a locking time and to reduce power consumption in a solenoid by locking a carriage with a permanent magnet in a seek motor and spring force and holding a release state with the solenoid.

CONSTITUTION: The solenoid 8 is turned off at a locking time, and a lock member 6 is moved in a left direction by the pressing force of a coil spring 10. Then, a magnetic member 7 provided on the lock member 6 is abutted on a back yoke part 3B, and is attracted by the permanent magnet 4 on the inner side surface of the back yoke part 3B. Simultaneously, the lock arm 1L of the carriage 2 and the U groove 6a of the lock member 6 are engaged, and the carriage is locked. Then, the force of the spring 10 for obtaining prescribed holding force is weakened as compared to the case of holding by only the force of the spring 10, and drive energy consumption in the solenoid 8 releasing the lock is reduced.