Abstract: A process for improving chemical and physical adhesive properties of an adhering surface of an unsaturated polyester resin to be adhered onto an article prepared from the unsaturated polyester resin which includes:laying a cloth on a portion of a mold, the cloth having a strong adhesivity for the unsaturated polyester resin;impregnating the cloth with the unsaturated polyester resin and leaving the impregnated resin on said mold for hardening for a given time to form a sheet; andstripping the cloth which is impregnated with the hardened unsaturated polyester resin from the unsaturated polyester resin to form an irregular or rugged adhering surface.