We propose the synthesis of photopolymers having pendant cinnamic ester by the addition reaction of poly(glycidyl methacrylate)[poly(GMA)] with cinnamoyl chloride. Quaternary ammonium salts showed good catalytic activity for this synthesis. Photochemical reaction experiments revealed that photopolymer bearing cinnamoyl groups has good photosensitivity which was enhenced by the photosensitizer in the synthesized photopolymer