Polymeric ultraviolet absorbers were prepared from 2-hydroxy-4-acryloyloxybenzophenone and 2-hydroxy-4-methacryloyloxybenzophenone and their inhibitive effect for photodegradation of polyethylene were examined by measuring mechanical strength, melt index, carbonyl group, and color difference. The polymeric ultraviolet absorbers were superior to the same type of ultraviolet absorber with low molecular weight in many properties, but inferior to Tinuvin, a commercial reagent, which has a different molecular structure. Therefore, within the ultraviolet absorbers examined, molecular structure seems to be a more important factor than molecular weight.