To provide an air flow type pulverizer provided with a sieving rotor having impeller pins whose core material is reusable.

The air flow type pulverizer comprises (a) a pulverizing chamber, (b) a material supply pipe provided on the lateral wall of the pulverizing chamber, (c) a plurality of pulverizing nozzles provided on the lateral wall lower than the material supply pipe for pulverizing by accelerating and bombarding to form a fluidized bed of the pulverized powder, (d) a sieving rotor, provided at the upper part in the pulverizing chamber, sieving a fine powder from a solid-gas mixture flow which breaks away and ascends from the fluidized bed of the pulverized powder and having a hollow cylinder part formed of an upper plate, a lower plate and a urethane resin provided between the upper plate and the lower plate and a plurality of impeller pins having core materials detachably inserted into the hollow part and connected to the upper plate and the lower plate with their both end parts, and (e) a fine powder collecting device, transporting the fine powder out of the pulverizing chamber, provided with a collecting opening at the distance less than 0.2 mm from the discharging outlet of the sieving rotor.