To keep appearance excellent by processing an end part of a skin integrated resin molded article so that sections of a base, a cushion foam material and others may not seen from outside by a simple end part processing wherein the end part is pressed and heated.

The end part side (r) of a skin integrated resin molded article R made to protrude laterally from a backing face 1a of a backing jig 11 is pressed from the skin material 3 side by a heating plate 10 made to heat to a temperature of a melting point of a thermoplastic resin base 1 or above and thereby the base 1 is softened by heating and bent to the direction perpendicular practically to the backing face 1a of the backing jig 11. Thereby the end part side (r) of the skin integrated resin molded article R is formed to be faced with a skin material 3.