A light-sensitive composition comprising a light-sensitive resin selected from the group consisting of a cinnamic acid resin, a cinnamylidene acetate resin and a cyclized rubber resin, and a xylene resin is disclosed.

A light-sensitive lithographic printing plate comprising a support and a layer of a light-sensitive composition thereon consisting of a light-sensitive polymer containing a --CH.dbd.CHCO-- unit in its main chain and a light-sensitive polymer containing a --CH.dbd.CHCO-- unit in its side chain(s).

A high polymer compound containing therein the reactive group represented by the following general formula; ##STR1## wherein X represents O or S; Y represents a hydrogen atom or a cyano group; and R.sub.2 represents a hydrogen atom, an alkyl group having not more than 4 carbon atoms, a halogen atom or a nitro group.

The novel polymers disclosed have the formula: ##STR1## wherein R.sub.1 is R.sub.5 --(z).sub.p ; R.sub.5 is a terminal reactive group --O--; z is --isocyanate--O--; p is zero or 1, however p is zero when m is zero; P .sub.1 is an organic radical; m is zero or 1, however m is zero when n is 1; R.sub.2 is an organic radical; i is an integer from 2 to 6; P.sub.2 is an organic radical; r is zero or 1, however r is zero only when m is zero and n is zero; R.sub.3 is an organic radical; P.sub.4 is the residue from a polyhydroxy compound; n is zero or 1; R.sub.4 is --(v).sub.w --R.sub.6 ; v is --O--isocyanate; w is zero or 1, however, w is zero when m is zero; and R.sub.6 is --O-- terminal reactive group. The polymers are preferably made by first reacting a dianhydride with a polymer having terminal hydroxy groups and then reacting the reaction product with a hydroxy group terminated acrylate or methacrylate or a hydroxy group terminated hydrogen donor containing at least one heterogeneous atom such as O, N, or S. Polymer compositions comprising these polymers have been found to be very useful as photoresists in producing printed circuit boards.