This invention provides a disk holding device which may include a plurality of disk holding members and a disk receiving part. The disk holding members may each be provided with a holding projection part projected from the inner periphery side toward the outer periphery side of the disk-formed recording medium; the holding projection part may be provided with an inclined surface displaced so as to be spaced away from the disk-formed recording medium as one goes from the inner periphery side toward the outer periphery side of the disk-formed recording medium in the condition where the disk holding members are inserted in the center hole.