A photopolymerizable dental composition, which comprises:(A) an organic composite filler obtained by polymerizing a sulfonic acid or sulfonate monomer of the formula: ##STR1## wherein R.sub.1 is a hydrogen atom, a C.sub.1 -C.sub.20 alkyl group, a phenyl group or a derivative thereof, or a halogen atom; ##STR2## wherein each of R.sub.2 and R.sub.3 is a hydrogen atom or a C.sub.1 -C.sub.15 alkyl group, R.sub.4 is a C.sub.1 -C.sub.15 alkylene group, m is an integer of from 1 to 20 and n is an integer of from 0 to 20; and Y is a hydrogen atom, NH.sub.4 or an alkali metal atom, and at least one radical polymerizable vinyl monomer in a polymerization system in which an inorganic compound is dispersed;(B) a monomer mixture comprising 2,2-bis[4-(methacryloxyethoxy)phenyl]propane, at least one hexa-functional urethane (meth)acrylate of the formula: ##STR3## wherein X is ##STR4## wherein n is an integer of from 1 to 10, and each of R.sub.1 and R.sub.2 which may be the same or different is a hydrogen atom or a methyl group, and a diluting ethylenic vinyl monomer; and(C) a photopolymerization initiator comprising an .alpha.-diketone compound and a reducing agent, wherein the reducing agent is at least one member selected from the group consisting of diaminobenzophenone compounds of the formula: ##STR5## wherein each of R.sub.1 to R.sub.4 which may be the same or different is a hydrogen atom or a C.sub.1 -C.sub.5 alkyl group, provided that at least one of them is the alkyl group, and C.sub.5 -C.sub.10 alkyl esters of 4-(N,N-dimethylamino)benzoic acid.