A homogenizer is disclosed, which can produce an emulsion with a grain diameter as extremely fine as approximately 1 μm without using large-scale equipment such as a high-pressure pump, and in which a grain diameter distribution of the produced emulsion exhibits sharp characteristics in the vicinity of a target grain diameter. A fixed portion and a disc-shaped agitation rotor are arranged in an opposing manner through a predetermined clearance to constitute a thrust hydrodynamic bearing, and while supporting a rotation of the agitation rotor with respect to the fixed portion by the thrust hydrodynamic bearing, a plurality of mutually incompatible raw liquids A and B are introduced into the bearing clearance to be mixed and agitated in the bearing clearance in accordance with the rotation of the agitation rotor.