Processing device for uniformly grinding wafers held by a plurality of chucks, and a method for setting the processing device. A processing device includes a coarse grinding device and a fine grinding device that are provided in a column straddling over a holding device. The holding device includes: an index table; chucks concentrically disposed about a rotation shaft; a first movable support unit on the outer peripheral side of the chuck in the radial direction of the index table; and a first fixed support unit on the inner peripheral side of the chuck in the radial direction of the index table. The first movable support unit is interposed between the index table and the chuck, and can be freely expanded and contracted in a vertical direction.