There are provided an inorganic filler, multi-functional filler, an organic compound filler, a modified filler, and a dental coloring filler suitable in use as a filler in a dental composition, compositions having a resin matrix of an organic polymer material, as well as a process for producing the same. Disclosed are an inorganic filler which comprises an inorganic fine particle, wherein the surface of the inorganic fine particle is covered with polysiloxane. Also disclosed is a multi-functional filler which comprises an inorganic fine particle containing an acid reactive element, wherein a cement reactive phase is formed on the surface of the inorganic fine particle, and the cement reactive phase is further covered with polysiloxane. Also disclosed is an organic compound filler which comprises an organic-inorganic polymer particle or an organic polymer particle, wherein the surface of the organic-inorganic polymer particle or an organic polymer particle is covered with an inorganic film. Also, disclosed is a modified filler which comprises an inorganic fine particle, wherein the surface of the inorganic fine particle is covered with polyorganosiloxane. Also disclosed is a dental col ring filler, which comprises an inorganic particle and a coloring particle, wherein the inorganic particle and the coloring particle are unifoy mixed and dispersed, the surfaces of these particles are covered with poly(organo)siloxane. Further disclosed are dental compositions containing above fillers, and processes for producing above fillers.