PURPOSE: To continuously prepare a dispersion in uniform distribution of liquid- drop diameter within a short time, by supplying a dispersion phase as a dispersion in a pre-dispersing state on the way in a continuous phase supplying pipe and applying shearing force by a rotating cutter to the pre-dispersion passing pores in side walls of an inner cylinder and sprayed to sides.

CONSTITUTION: A continuous phase supplying pipe 1 to supply a continuous phase, a dispersion phase supplying pipe 3 to supply a dispersion phase on the way of the continuous phase supplying pipe 1, and a dispersing part 8 to disperse the supplied dispersion phase to the continuous phase are fitted. Further, the dispersing part 8 is composed of an inner cylinder 9 connected to the continuous phase supplying pipe 1 and having a plurality of pores 10 in the side walls, an outer cylinder formed in the outside of the inner cylinder 9 and having a plurality of slits 12 in the side walls, and rotating cutters 13 put between the inner cylinder 9 and the outer cylinder 11 and set to rotate. As a result, a dispersion in uniform distribution of liquid-drop diameter is prepd. within a short time continuously.