A molded synthetic resin product comprising a synthetic resin substrate and a coating layer formed by heat treatment on the surface of the substrate, said coating layer comprising, as main components, (A) a silane compound having a hydrolyzable group directly bonded to a silicon atom, and (B) an acrylic resin obtained by polymerizing a monomer selected from the group consisting of alkyl (meth)acrylates, or a mixture of such a monomer with an alkenyl benzene monomer, and a copolymerizable .alpha.,.beta.-ethylenically unsaturated monomer.