Disclosed herein are a fuel cell separator having gas supply grooves on one side or both sides thereof which is molded from a composition composed mainly of an electrically conductive carbon powder and a binding agent, wherein the electrically conductive carbon powder is present such that its particles longer than 70 m at maximum in the major axis direction and longer than 30 m at maximum in the minor axis direction along the vertical cross section of the fuel cell separator occupy more than 50% of the sectional area in the vertical direction, a process for production of the separator, and a polymer electrolyte fuel cell.