Abstract: A window for automobiles or the like includes a window plate and an integral frame member along at least one edge of the window plate. The window is manufactured by preparing a window plate and a pre-shaped frame body which comprises a main portion and a surface layer covering an outer side of the main portion. The main portion of the pre-shaped frame body is composed of a thermoplastic synthetic resin material having a relatively high dielectric loss and containing a heat foamable agent therein. The surface layer is composed of a non-foamable thermoplastic synthetic resin material. The pre-shaped frame body is subjected to a dielectric heating in a mold, to cause the foamable agent in the main portion of the pre-shaped frame body to expand in the mold cavity.