Disclosed is a processing device that performs processes such as compositing by applying strong pressure or shear force to granular materials. Said processing device, which has a simple structure and can easily find optimal processing conditions, is provided with: a vertical mixing vessel (20); a rotating shaft (30) inserted through the bottom of the mixing vessel (20); a plurality of stirring blades (40) provided on the rotating shaft (30); and a plurality of impact plates (50) affixed to the mixing vessel (20). Letting the diameter of the mixing vessel (20) be d, the minimum distance between the stirring blades (40) and the impact plates (50) is at most 0.1d.
