Abstract: A coating composition that can be applied to optical plastic moldings having a high refractive index, to protect them from deterioration by light without any adverse effect on their optical functions. The coating composition contains the following essential constituents.(A) 1 part of a hydrolyzate of a silane compound;(B) 0.2-5 parts of titanium oxide-based composite fine particles having a particle diameter of 1-100 nm in which titanium oxide integrally combines with iron oxide, with the ratio of iron oxide to titanium oxide being 0.005-0.15 by weight;(C) 0.02-0.5 part of an unsaturated or saturated polycarboxylic acid or an anhydride thereof; and(D) 0.01-0.2 part of a heat-curing catalyst.