Abstract: A composite filler obtained by precuring the acrylate or methacrylate of a polyhydric alcohol having at least three ethylenically unsaturated groups in the molecule thereof by using a free-radical initiator in the presence of an inorganic filler, followed by grinding the resultant prepolymer is described. This composite filler remarkably improves the stiffness and hardness of organic resins and rubbers, and prevents a decrease in the impact strength and bending strength of organic resins and rubbers when the composite fillers are compounded into the organic resins and rubbers. Furthermore, a dental composition obtained from the polymerization of a vinyl compound in the presence of the above-mentioned composite filler is described. This dental composition has excellent properties, such as, high hardness, high strength, good adhesiveness, and is suitable for use as dental materials.