PURPOSE: To fix reliably a surface slide zipper to a cavity surface by making removal of a plastic film easy, by a method wherein a predetermined recessed part and jetty are formed on the cavity surface, the surface slide zipper is mounted so that an external fringe of the surface slide zipper is stuck to an inner wall of the jetty and liquid foamed stocks are cast.

CONSTITUTION: A molded 30 possesses a cavity 36 of a desired form, forms a jetty 38 surrounding an external fringe of a surface slide zipper 34 on a predetermined part of a cavity surface 32 on which a surface slide zipper 34 is mounted and recesses 42 holding hooks 40 of the surface slide zipper on the cavity surface surrounded by the jetty 38. The surface slide zipper 34 is fixed reliably and strongly within the jetty 38 of the cavity surface 32 through adhesion between an external fringe of the surface slide zipper and an inner wall of the jetty and surrounding of the external fringe of the surface slide zipper with the jetty 38. Liquid foamed plastic stocks 22 cast within a mold cavity 36 filled into the cavity 36 through foaming and the surface slide zipper is stuck close to a regular position in the surface of a foamed molded product.