A cartridge slot door mechanism is disclosed that covers a cartridge slot arranged at a front panel of a frame. The cartridge slot door mechanism includes an upper door having an upper side supported by the front panel, and a lower door having a lower side supported by the front panel. The upper door and the lower door are configured to open toward the inner side of the frame, and a lower side portion of the upper door and an upper side portion of the lower door are arranged to overlap.