A media-agitation type wet disperser is provided which eliminates the group motion of media, attains high dispersion efficiency, and avoids wear problem. A cylindrical vessel having a feed opening for the treating material and a discharge opening for the treated material is equipped with a cylindrical separator and a rotor rotating while being fixed to a rotary shaft. The rotor is composed of pluralities of small rotors each having a cylindrical agitation part and a disk-shaped holding part. The agitation part has pluralities of throughholes connecting the inside and the outside thereof.