PURPOSE: To prevent the functional disorder of a working part and also make an integral foamed sheet at a low cost by covering entirely the working part fitted on a frame with a resin film and molding a pad by means of integral foaming of a synthetic resin.

CONSTITUTION: The whole of a head rest frame 1 or almost all the head rest frame 1, except a minimum number of holes required to fit the frame 1 to a pad 2 etc., is covered in advance with a synthetic resin film 4 by means of heat molding or vacuum molding, and then the head rest frame is set in a pad mold, a synthetic resin such as urethane and others is injected and foamed integrally to mold the pad 2. Accordingly, because the resin film 4 prevents the foamed substance from penetrating into the inside of the frame 1, the occurrence of functional disorder on a working part 3 is protected. In addition, the production cost is reduced owing to the simple process and cheap resin film.