PURPOSE: To strengthen the bonding properties among a trim skin material, a molding and an ornament by a method wherein the forming of the trim skin material and the filling and molding of synthetic resin material are done under the condition that the ornament fixed by the molding is arranged in a vacuum forming mold.

CONSTITUTION: An ornament 4, the peripheral edge parts 4A of which are positioned so as to cover molding fixing ribs 11A on the molding surface 8A of a lower mold 8, is set to an ornament seating part 10A and, after that, a molding 5, which is positioned so as to face its inserting groove 5A downward, is pressed against the molding fixing ribs 11A so as to be inserted in the molding fixing rib 11A. After that, a preheated trim skin material 2 is arranged so as to cover the whole molding surface 8A of the lower mold 8 and, after an upper mold 9 is set onto the lower mold, the trim skin material 2 is vacuum- formed by actuating a pressure reducing means. Finally, foamable synthetic resin material 6 for molding base material is fed onto the trim skin material 2, and spread over the whole trim skin material 2 for molding.