With a conventional disk changer, it takes a long time with poor operability to directly and visually confirm which tray has a disk or which tray has which disk in a device. A disk changer of the invention includes a tray transfer unit for shuttling trays between a standby position and an attaching/detaching position and between the standby position and a recording/reproducing position, a tray gear unit engaged separately with the trays, and a tray driving unit for driving the trays separately via the tray gear unit, so that the trays can be separately moved from the standby position to the attaching/detaching position via the tray gear unit and the trays can be protruded to the attaching/detaching position while being arranged like steps. Hence, it is possible to directly and visually confirm which tray has a disk or which tray has which disk in a device with a simple operation in a short time.