PURPOSE: To improve quality of trimming by reducing operation manpower, by a method wherein after a skin material has been shaped by unifying it with an ornament through vacuum molding, liquid foamed plastics raw materials are poured on the skin material for foaming.

CONSTITUTION: An ornament 2 is placed on a predetermined position of a vacuum molding tool 1 having a cavity in a shape of an interior trimming material, a skin material 3 made of soft vinyl chloride resin leather is softened by heating the same, vacuum molding is performed through the vacuum molding tool 1 whereon the ornament 2 has been placed and both of them are made to unify through an adhesive agent. After foamed plastics raw materials have been poured into a hollow part formed on the top of the skin material 3 the vacuum molding tool 1 is covered with a lid 5 serving as an upper force, a liquid foamed plastics raw material 4a is made to foam and a foam layer 4 is formed. In this instance, a molded material is shaped in a shape running along the surface of the cavity.