Abstract: A photopolymerizable composition comprising (i) a polymerizable compound having an addition polymerizable unsaturated bond, (ii) a compound represented by formula (Ia): ##STR1## a compound represented by formula (Ib): ##STR2## or a compound represented by formula (Ic): ##STR3## wherein A represents an oxygen atom, a sulfur atom, a selenium atom, a tellurium atom, an alkyl- or aryl-substituted nitrogen atom, or a dialkyl-substituted carbon atom; Y.sup.1 represents a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, an aralkyl group, an acyl group, an alkoxycarbonyl group, or a substituted alkoxycarbonyl group; R.sup.1 and R.sup.2 each represents a hydrogen atom, an alkyl group having from 1 to 18 carbon atoms, or an alkyl group having from 1 to 18 carbon atoms which is substituted with R.sup.3 O--, ##STR4## or a halogen atom (i.e., F, Cl, Br, and I), wherein R.sup.