Abstract: A pulverized starting material is supplied quantitatively from a quantitative feeder 1 to a first mechanical pulverizer 2 where the material is pulverized moderately, the resulting moderately pulverized material is supplied quantitatively from a quantitative feeder 3 to a second mechanical pulverizer 4 where the material is finely pulverized, and the resulting finely pulverized material is introduced into a coarse-powder classifier 5 to classify coarse powder not smaller than a predetermined particle diameter. The finely pulverized material from which the coarse powder was removed by classification is further classified fine powder not larger than a predetermined size by a fine-powder classifier 7 to produce a classified product, while the separated classified coarse powder is introduced into a returning-powder feeder 6.