A linear actuator has a flat box-like carriage movable along an access direction of a disk as a recording medium, a motor coil housed and fixed in the carriage, and a permanent magnet arrangement housed and fixed in the carriage to apply a magnetic field to the motor coil. The permanent magnet arrangement includes an E-shaped yoke member with a central portion extending along the access direction and inserted in the motor coil, a pair of outer portions arranged along two sides of the central portion, and permanent magnets arranged on opposite surfaces of the outer and central portions. The yoke member is arranged in the carriage to be parallel to the disk.