Disk apparatus with sliding tray and lock arm for preventing sliding tray movement

A disk apparatus comprises a tray for mounting a disk thereon, a lock arm for locking the tray to a main body chassis and releasing this locking, a coil for operating the lock arm by an electromagnetic force, a coil holder for holding the coil and transmitting the electromagnetic force to the lock arm, a magnet for applying a magnetic flux necessary for the operation, a rail for holding the tray to the main body chassis and guiding an accommodation/ejection operation, a push block for pushing out the tray, a push spring for operating the push block, an eject button pushed down when the user wants to eject the tray, a detention switch for detecting the push-down of the eject button, and a controller for applying a voltage to the coil upon receiving the detection information. The entire thickness of the tray lock mechanism is composed no more than 5 mm and is accommodated in the rear internal space of the recess so that a disk apparatus reduced in the thickness in the height direction of the outer case is presented.