A disk recording-reproducing apparatus ensures a large transport distance of a tray which moves a disk-shaped recording medium between an ejecting position and a recording-reproducing position while decreasing a dimension in the transport direction. A drive section (47) is built into a tray (13) which can be extracted from and retracted into an external chassis (10) and moves a disk-shaped recording medium between the ejecting position and the recording-reproducing position. A pinion (56) comprises an output end of the drive section (47) and rolls on a rack (24) of a chucking slider (20) to self-propel the tray (13). After the tray (13) completely moves to the recording-reproducing apparatus side, an output from the drive section (47) of the tray (13) is used to move the chucking slider (20) to the ejecting direction of the tray (13). Then, a cam groove (23) provided on the chucking slider (20) is used to raise a base unit (30).