An object of the present invention is to provide a photopolymerizable dental composition which causes less change in a color tone before and after curing and exhibits excellent photopolymerizability to irradiation in a wide wavelength range, and has also excellent thin-layer surface curability, and to provide a photopolymerization initiator used therefor.Disclosed is a visible light-polymerizable dental composition which does not substantially contain an amine compound as a photosensitizer, comprising 0.01 to 10 parts by weight of a (bis)acylphosphine oxide compound, 0.01 to 10 parts by weight of an α-diketone compound and 100 parts by weight of a polymerizable monomer.