Abstract: The present invention relates to a multi-tray optical disc device and tray lock mechanism thereof. The tray lock mechanism includes a magazine which accommodates trays each having an indentation; a sliding cover provided with trenches; and an elastic sheet provided between the magazine and the sliding cover, the elastic sheet also includes plural spring strips each having a hook part and an extrusion part. During the sliding of the sliding cover, it can select to unlock one or all disc trays or lock all disc trays. According to the tray lock mechanism of the present invention, it is possible to prevent trays from falling suddenly out from the magazine due to gravity and shaking when user draws the cartridge out from the disc device.