Also, a plurality of disks can be efficiently ejected and loaded in a short time.BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are a plan view and a side view, respectively, of a disk device according to an embodiment of the present invention while no disk is accommodated therein and a driving unit is disposed at a playback position; FIGS. 2A and 2B are a plan view and a side view, respectivel