PURPOSE: To comparatively low inhibit production cost and to diminish heat evolution and contamination by repeating a crushing stage at a plurality of times by a pressure roller device and there after and grinding the flaky raw material produced in the crushing stage by a flake breaker to pulverize the same.

CONSTITUTION: A raw material crushed by a pair of pressure rollers 6A, 6B is compressed and becomes a corrugated flaky shape and then is discharged to a tank 1 of the raw material. A crushing stage is repeated at a plurality of times. At a point of time when the raw material is sufficiently crushed, the compressed flaky raw material is supplied to a flake breaker 7 and crushed by the blades rotated at high velocity to produce fine powder. The pulverized raw material is sieved by a screening device 8 and required fine powder is discharged from an outlet 10. Thereby fine powder is produced at comparatively low cost without necessitating freeze grinding and a freeze drying stage. Further heat evolution and contamination are diminished and good-quality fine powder is obtained.