A photopolymerizable composition comprising an addition polymerizable unsaturated compound having at least two ethylenically unsaturated double bonds in the molecule, a photopolymerization initiator, and a binder, wherein the binder is a tetrapolymer having a weight average molecular weight of from 10,000 to 50,000 represented by formula (I): ##STR1## wherein R represents a hydrogen atom or a methyl group; and w, x, y and z each represents mol percent (mol %), w ranging from about 45 to 65; x ranging from about 5 to 18; y ranging from about 2 to 10; and z ranging from about 20 to 40 and where C.sub.4 H.sub.9 (n) represents an n-butyl group. The photopolymerizable composition can be developed with a weakly alkaline aqueous solution, has sufficient flexibility to be laminated on a base as a dry film, high adhesiveness to a base and reduced surface tackiness. It resists cold flow during preservation, has excellent resistance to swelling by a developing solution after polymerization, and rapid releasability when treated with a dilute aqueous solution of a strong alkali containing no organic solvent, and forms an image faithful to the original with a high resolving power.