To obtain a dental composition without having a biological safety issue, and having a high surface-curing property, a high degree of polymerization, a high curing depth and a short light irradiation time in spite of having a high preservation stability.

This composition contains a polymerization initiator and a polymerizable organic material, and the polymerization initiator is expressed by formula (1) [R3, R4 are each an alkyl; and R1, R2 are each an electron-withdrawing group, an alkyl, or the like], has ≤1,000 molecular weight and also consists mainly of a compound containing 17-54 % ratio of the following structural part in formula (2) based on mass basis in the compound.