Separator for fuel cell and process for producing the same

The present invention provides a separator for fuel cell containing: a flat plate member (6); a gas passage-side member (7a) provided on one side of the flat plate member and having passages (8a) for passing a reactant gas therethrough; and a cooling water passage-side member (7b) provided on the other side of the flat plate member and having passages for passing cooling water (8b) therethrough, wherein the gas passage-side member and the cooling water passage-side member are formed from first and second conductive resin compositions which are different from each other, respectively, and the difference between the thermal expansion coefficient of the gas passage-side member in its thickness direction and the thermal expansion coefficient of the cooling water passage-side member in a direction perpendicular to its thickness direction is 25 x 10/K or smaller, and wherein the flat plate member contains at least one of the first and second conductive resin compositions.