To make a device small and inexpensive and improve the crushing efficiency by feeding a rough powder in exhaust flow into between a lower disk and an upper disk of an upper side central section of a rotating impeller, feeding again the rough powder to the inner peripheral face of a rotating path casing and crushing repeatedly.

Matters to be crushed fed from a feed tube 32 onto a lower disk 26 of a rotating impeller 25 are fed in the outer peripheral direction of the rotating impeller 25 while being in collision with blades 29 and the like by the rotating impeller 25 at a high speed. The matters to be crushed are further crushed by a high speed rotating air flow layer flowing along the inner peripheral face of a rotating path casing 23 and fed to a central section of the rotating path casing 23 by the exhaust flow on the upper side of an upper disk 27. Rough powders in the exhaust flow are returned to the high speed rotating air flow layer by the rotating air flow flowing in the direction reverse to the exhaust flow along the upper face of the upper disk 27, and also returned to the high speed rotating flow layer through the inside of the rotating impeller 25 by the air flow flowing from a recovering case 30 and a feeding-in tube 32 into the rotating impeller 25, and further crushed into a fine powder and recovered into the recovering case 30 by the exhaust flow.