Jet mill

A jet mill has a disk-shaped hollow part in the interior of the mill body. The hollow part is divided into an annular grinding zone for grinding a material by high-speed swirling air flows supplied through plural air nozzles and an annular classifying zone provided inside the grinding zone and communicated to an exit space for classifying the ground material by the swirling air flows in the grinding zone. An annular first constricted passageway is arranged between the grinding zone and the classifying zone to thereby divide and communicate them, and preferably an annular second constricted passageway between the classifying zone and the inside exit thereof. Accordingly, a jet mill realizing a high classification precision for a desired particle size of ground material with a narrow size distribution and having a simple inner configuration to allow easy cleaning before and after operation can be provided.