The present invention can suppress variations in dispersion and grinding processing, apply stable shearing force to a material to be processed, and also enable efficient dispersion and grinding. The present invention has a supply portion (10A), a processing portion (10B), and a discharge portion (10C). The processing portion (10B) includes a stator (12b), and a rotor (11b). The material to be processed is processed in a gap (Gt) between an outer peripheral surface of the rotor (11b) and an inner peripheral surface of the stator (12b). The inner peripheral surface of the stator (12b) and the outer peripheral surface of the rotor (11b) are circular in a cross section orthogonally intersecting the axis of the rotor (11b) and linear in a cross section bearing the axis. The gap (Gt) is constant in the circumferential direction and the axial direction.