A coated plastic molded article composed of a plastic article on the surface of which laminated are (a) a first layer composed of a cured composition containing a partially hydrolyzed product of at least one silicon compound, (b) a second layer composed of a cured, partially hydrolyzed product of another silicon compound, and (c) a third layer composed of the silicon dioxide from an aqueous hydrosilicofluoric acid solution supersaturated with silicon dioxide, by the order of (a), (b) and (c) ; and a process for preparing the coated plastic molded articles.