To provide a particle classifier with excellent classification efficiency.

A particle dispersion A is characteristic in that the specific gravity of a particle is larger than that of a dispersion medium. The particle dispersion A is sent to a first classification path 101 from a particle dispersion introduction aperture 141. During sending the particle dispersion A through the classification path 101, the particle with a large particle diameter (referred to as "coarse particle") found in the particle dispersion A, reaches the bottom surface (lower surface in the vertical direction) 151 of the first classification path 101 on account of high sedimentation rate of the particle. On the other hand, a particle with a small particle diameter (referred to as "microparticle") is directly released without reaching the bottom surface 151, from a microparticle dispersion discharge aperture 121 arranged downstream of the classification path 101.