To prevent fine particles turning in a classifying chamber from being stayed by changing a pattern of a turning air flow.

Inclination of an under side surface 16 of a central core 7 is different from that of an upper side surface 17 of a separator core 9, and a reduced flow or a magnified flow is generated in the classifying chamber 4 formed between them. A circular member 23 having a shape fitting to the under side surface 16 and having a cavity at one part of center is placed at the under side surface 16 and adhered to realize the objective dispersion separator(DS) type classifying device. In this way, the under side surface of the circular member 23 becomes the under side surface 16. By this constitution, the staying of the fine particles is evaded, moreover, the evading of a reaggregation of the fine particles due to the staying and a highly accurate classification are executed and a total classifying yield is improved because a moving is caused in a direction along a central shaft 19 to the fine particles staying while turning under a balance of force on the under side surface 16 or the upper side surface 17.