The present invention provides a simple disk drive and drive unit driving mechanism with compact size in which each part is able to operate smoothly. The disk drive and drive unit driving mechanism comprise a disk holder 10 that has a plurality of holder plates 11 that individually hold disks D, a drive unit 62 that plays back disks D, disk selectors 41A and 41B that form a space above and below a desired disk D by raising and lowering the holder plates 11, and a drive base 60 that moves the drive unit 62 into a space that is formed by raising and lowering the holder plates 11. The disk selectors 41A and 41B are provided with flat cams 41Aa to 41Ac and 41Ba to 41Bc in which the protrusion 14 a provided on the holder plate 11 is inserted so as to be capable of performing a sliding movement, such that the tips of the cams are wedge-shaped. The holder plates 11 above and below the desired disk D rise and fall in accordance with the sliding movement of the disk selectors 41A and 41B.