PURPOSE: To protect a floppy disk not to be damaged and its recording contents not to be altered, by spacing a magnetic head from a floppy disk surface to lock the head.

CONSTITUTION: When a DC voltage 1 drops below the level having a prescribed voltage, a voltage level detecting circuit 2 outputs a detection signal. This detection signal operates a head locking mechanism 3 which spaces the magnetic head from the floppy disk surface to lock the head. Once the magnetic head is spaced from the floppy disk surface and locked, an automatic ejector mechanism 4 which ejects the floppy disk out of a disk driver body is released by the signal from the detecting circuit 2. Consequently, the floppy disk is taken out of the disk driver.