TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: The reducing compound is amine derivative of formulae (a-e), and amine derivative of formula: (Rb1)-N(OH)(Rn1), Rb2-C(=O)-N(OH)(Rn2), (Rb3)-N(Rh3)-C(=O)-N(OH)(Rn3), Rb4-O-C(=O)-N(OH)(Rn4), Rb5-N(Rh5)-N(Rh5)-C(=O)-N(OH)(Rn5), Rb60-C(X6)=C(X6)-C(=X6)-Rb61, (Rb110)(Rb111)N-N(Rb112)(Rb113), or Rb12-N(Rh12)-N(Rh12)-C(=O)-X12, and is contained in catalyst film(s).Rb1-Rb5,Rb70,Rb71,Rb110-Rb113,Rb12,Rb13,Rn1-Rn5=H, alkyl, aryl, or heterocyclic;Rh3,Rh5,Rh5,Rh12,Rh12,Rh13=H alkyl, aryl, acyl, alkylsulfonyl, or arylsulfonyl, where Rh3 is hydroxyl group;Rb100,Rb101,Rb102,Rb130-Rb133=H or substituent;Y7,Y8=substituent excluding hydroxyl group;Y9=substituent;m7=0-5;m8=1-5;m9=0-4;m7,m8,m9=2 or more;Z10=non-metallic atom group which forms ring;X12=H, alkyl, aryl, heterocyclic, alkoxy, amino (including alkylamino, aryl amino, heterocyclic amino, or cyclic amino group) or carbamoyl group;X6,X6=hydroxyl, alkoxy, mercapto, alkylthio, amino group (including alkylamino, aryl amino group, heterocyclic amino or cyclic amino group), acylamino, sulfoanamide, alkoxy carbonylamino, ureido, acyloxy, acylthio, alkyl aminocarbonyl oxy, or aryl aminocarbonyl oxy, or aryl aminocarbonyl oxy;Rb60,Rb61=alkyl, aryl, amino, alkoxy or aryloxy, and form cyclic structure;andY6=oxygen or sulfur atom.Y7-Y9 are coupled together to form aryl group condensed benzene ring optionally having substituent.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The polymer electrolyte membrane contains sulfonated aromatic polymer in which sulfonate portion(s) is provided in aromatic ring, preferably sulfonated polysulfone in which sulfonate portion(s) is provided in deactivated aromatic ring adjacent to sulfone functional group of polysulfone. The polyelectrolyte contains aromatic repeating unit of formula (I). The aromatic polymer contains alkyl sulfonyl group of formula (3): -(CH2)n-A. The electrolyte membrane contains electroconductive material consisting of carbon material containing fine particles of catalyst metal, and binder containing repeating unit of formula (I). The binder is dispersion liquid containing ionic polymer particles having volume average particle size of 1-200 nm.n/(n+m)=0.001-1, preferably 0.1-0.8;Y=-S-, -S(O)-, -S(O)2-, -C(O)-, -P(O)(C6H5)-, preferably -S(O)2- or -C(O)-;Z=single bond, -C(CH3)2-, -C(CF3)2-, -C(CF3)(C6H5)-, -C(O)-, -S(O)2- or -P(O)(C6H5)-, preferably single bond or -C(CF3)2- ;A=sulfonate group or -B1-(X-B2)m1-SO3M;B1,B2=coupling group;X=group containing sulfur atom;M=cation;m1= greater than or equal to 1;n=1, 2, 3, 4, 5, or 6;andA=sulfonate portion of proton-type, sodium-type or potassium-type.