A classifier capable of stably providing particles by further reducing the mixing ratio of coarse particles including a rotating fin (21) classifying solid particles by a centrifugal force, a cylindrical downward flow forming member (13) installed on the outer peripheral side of the rotating fin (21), a recovery cone (11) disposed under the rotating fin (21) and the downward flow forming member (13), and a housing (41). A contraction flow area (16) is formed between the housing (41) and the recovery cone (11), and a two-phase flow (52) formed of the mixture of the solid particles and gases blown up through the contraction flow area (16) is collided with the downward flow forming member (13) on the upper side of the housing (41) to form it in a downward flow. Then, that flow is led to the rotating fin side, classified into the fine particles and the coarse particles, and the fine particles are carried together with an airstream, passed through the rotating fin (21), and removed. A circulating swirl flow development suppressing part (30) is installed at the upper part of the contraction flow area (16) and on the outer periphery of the downward flow forming member (13).