Provided are a tray 2 for mounting a cartridge 101 that houses a disk and has an aperture for exposing an information layer and a shutter 101a for opening/closing the aperture, a conveyor for conveying the tray 2, an opener 13 having an engaging member and opening/closing the shutter 101a, and guiding members 14, 15, 16 arranged to engage with the opener 13 and interlocked with a conveyance operation of the tray 2 so that engagement position with an engaging member of the opener 13 changes, wherein the guiding members 14, 15, 16 are arranged opposing the face for mounting the cartridge 101. Thereby, there is no need for providing to the upper part of the cartridge 101 a system for opening/closing the shutter 101a, and thus a space below the tray 2 can be used effectively, resulting in downsizing of the apparatus.