A photopolymerizable composition comprising: (a) a compound obtained by reacting one mole of a polyamine represented by the following general formula (I) with at least 2 moles of a compound having a group capable of reacting with the polyamine and a polymerizable ethylenically unsaturated group: ##STR1## wherein n is an integer of not less than 1 and (b) a photopolymerization initiator.A dry PS plate comprises a substrate provided thereon with, in order, a light-sensitive resin layer and a silicone rubber layer wherein the light-sensitive resin layer comprises the photopolymerizable composition and a polymeric compound having film-forming ability.The photopolymerizable composition and the dry PS plate have very high sensitivity.