TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Method: The ion substitution process is carried out by contacting the surface of electrolytic membrane with a solution containing ammonium ion by immersing the membrane into the solution. The ion substitution process makes the counterion of 1-90% of cation exchange group into ammonium ion. Another ion substitution process which makes a hydrogen ion portion(s) of the cation exchange group, is carried out following the process of joining of catalyst layer. The catalyst layer is joined by hot pressing. Preferred Properties: The thickness of hydrocarbon-type polymer electrolytic membrane is 5-200 mu m. The elasticity modulus of electrolytic membrane at 120 degrees C when pre-supposing that all cation exchange groups are proton type groups, is 750-2000 MPa.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Group: The ammonium ion contains 3C or more alkyl group, and preferably is a quaternary ammonium ion. 90% or more of cation exchange group is a proton type group before making ammonium ion as counterion.    TECHNOLOGY FOCUS - POLYMERS - Preferred Unit: The hydrocarbon-type polymer electrolyte has an aromatic structural unit of formula: -(-Ar1-X1-)-.Ar1=bivalent aromatic group having optionally substituted 1-20C alkyl, optionally substituted 6-20C aryl, optionally substituted 1-20C alkoxy, optionally substituted 6-20C aryloxy, or optionally substituted 2-20C acyl;andX1=direct bond, -O-, -S-, carbonyl, or sulfonyl.At least one cation exchange group is coupled with the bivalent aromatic group in the aromatic ring directly. Preferably, the hydrocarbon-type polymer electrolyte is a block copolymer consisting of a block having cation exchange group and a block not having an ion-exchange group. The block having cation exchange group is of formula: -(-Ar11-X11-)d- or of formula (1).Ar11=Ar1;X11=X1;d=5 or more;R1=H, 1-20C alkyl, 1-20C alkoxy, 6-20C aryl, 6-20C aryloxy, or 2-20C acyl;J1=cation exchange group;andp=1 or 2.