To achieve forming and jointing of a resin member to a peripheral part of a fuel cell separator at low cost in a short time and with high dimension accuracy.

A plurality of through-holes 14 are formed along the end fringe 12 in a resin molding region 13 of a prescribed width along the end fringe 12 of a cutout portion 11 of a separator 10. In the state that the resin molding region 13 is set in a molding 30, the top end region 15 from the through-hole 14 to the end fringe 12 is supported so as not to be deformed by pinching by a deformation prevention pin 33 of top and bottom. A thermoplastic resin 21 is injected and filled into the molding 30 and a resin member 20 jointed to the resin molding region 13 is formed.