PURPOSE: To efficiently prepare an aqueous microdispersion within a short time by rotating discs through a drive shaft within a cylindrical vessel and providing parallel female screws to the inner surface of the vessel.

CONSTITUTION: Discs 7 are rotated through a drive shaft 4 within a cylindrical vessel 2 and the axial line of the vessel 2 is made freely rotatable while media and a material to be pulverized are strongly stirred. Parallel female screws 11 are provided to the inner surface of the vessel 2. When an aqueous dispersion of solid matter is treated using this hermetically closed type wet pulverizing apparatus, the starting of a stirring shaft can smoothly be performed and the clogging of a media dispersing mechanism is also eliminated and the generation of heat of a grinder can be suppressed low and extremely stable operation becomes possible and a pulverized solution can efficiently be obtained.