Provided is a disk device that improves the maintainability of a drive unit. This disk device comprises: a disk tray; and a disk selector that supplies, to a drive unit, a single disk from among a plurality of disks stacked on the disk tray. The disk selector includes: a disk selector spindle that supports the plurality of disks; a disk press against which an upper surface of a disk at the uppermost position of the plurality of disks, which are supported by the disk selector spindle, abuts; a displacement amount detection mechanism that detects the amount of displacement of the disk press which is displaced in accordance with the thickness of the plurality of disks being supported; and a thickness detector that detects the thickness of each of the plurality of disks on the basis of the detected amount of displacement of the disk press.