PURPOSE: To prevent a skin from rising without influencing the appearance or resiliency, by welding a skin to a cushion body by applying a specified welder mold onto a part of the skin that corresponds to the part of the cushion body where the cushion body rises from its seating section.

CONSTITUTION: A skin R is pressed to a resin material P inserted in the part extending from the seating section flat surface S1 of the cushion body C to the rising section S2 thereof, then the welder mold W wherein a pair of electrode rods W2, W3 are arranged in the same plane with an insulator W1 therebetween is pressed on the skin R, and an electric current from a DC power source E is passed through the electrode rods W2, W3 thereby securely welding the skin R and the resin material P. Thus, the skin can be attached to the cushion body without leaving an impression or the like on the surface of the skin or an indent in the cushion body.