PURPOSE: To provide a method for preventing foreign sound of a door trim end part for restraining foreign sound to be generated by rubbing against a door inner panel during driving of a vehicle.

CONSTITUTION: On a surface of a folded part 3a of a vinyl chloride skin 3 to be adhered to a base material 2, a heating plate 16 having a heating face formed into a rough face is butted so as to form a rough face by melting. Thus, the skin is folded at the end part so as to be adhered also to the rear face of the base material 2. When a door trim 4 having a shape to butt against a door inner panel at the end part is attached to the door inner panel, foreign sound to be generated by rubbing of the end part against the door inner panel during driving of a vehicle can be prevented.