A polymer containing triazine rings that has a molecular weight of 5,000-1,000,000 and that comprises a recurring unit represented by the general formula (I): ##STR1## wherein X.sup.1 and X.sup.2 are each independently S, NR.sup.1 (R is a hydrogen atom, an alkyl group or an aryl group) or O; Y may be an alkylene group, a divalent substituted or unsubstituted aromatic ring group that do not contain chromophore moieties or a group in which said aromatic ring groups are bonded or condensed together; Z is either a spacer group comprising a group represented by --G--(CH.sub.2).sub.n -- (n is an integer of 1-10) or a direct bond (G is S, NR.sup.4 or O, and R.sup.4 is a hydrogen atom, an alkyl group or an aryl group); and A is an organic chromophore moiety in which an electron donative group and an electron attractive group are conjugated via a .pi.-electron system. The polymer is lightproof, forms a thin film of high quality and has a high glass transition point.