PURPOSE: To give the number of degrees of freedom to the number of set disks by inclining respective disk placing planes of a turntable in a certain direction so that centers of revolving shafts of mounted disks are not parallel with the center of the revolving shaft of the turntable.

CONSTITUTION: On a turntable 11 where plural disks 12 are arranged with a uniform radius, disk placing planes 11B are formed which are inclined in a certain direction so that the center of a revolving shaft 13 of the turntable 11 is not parallel with centers of revolving shafts of mounted disks 12. Consequently, disks 12 are arranged on the turntable 11 while partially overlapping in the direction of the shaft of the turntable 11, and therefore, many disks 12 are held in a limited space on the turntable 11. Thus, the number of degrees of freedom is given to the number of set disks.