A photopolymerizable composition comprising an addition polymerizable compound having an ethylenically unsaturated double bond and a photopolymerization initiating composition, said photopolymerizable initiating composition comprising (a) a dye of the formula: ##STR1## [wherein R.sub.1 is H, an alkyl group having 1 to 3 carbon atoms, a phenyl group or a halogen atom; R.sub.2 is a methyl group, an ethyl group or (CH.sub.2).sub.p -Q (wherein Q is a carboxyl group, a sulfonyl group or salt thereof and p is an integer of 1 to 4); X.sub.1 and X.sub.2 are independently --O--, --S--, --CH.dbd.CH-- or >N--R.sub.2 ; Y.sub.1 and Y.sub.2 are independently H, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a phenyl group or a halogen atom; Z is --COO or --SO.sub.3 ; m is 0 or 1; and n is an integer of 1 to 4] and (b) diaryliodonium salt as a polymerization initiator.