TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The total amount of Lewis' acid property metal alkoxide and silicon oxide precursor in the proton conductor is 50-400 mol parts with respect to 100 mol parts of phosphoric acid compound. The amount of metal alkoxide in proton conductor is 5-50 mol parts with respect to 100 mol parts of silicon oxide precursor. The Lewis' acid property metal alkoxide contains titanium, aluminum or zirconium as Lewis' acid property metal. The silicon oxide precursor is alkoxide compound of silicon having proton dissociative group and alkoxide compound of silicon without having proton dissociative group. The proton dissociative functional group in alkoxide compound of silicon, is chosen from sulfonic acid group, phosphonic acid group, sulfonamide group, sulfonimide group and their derivatives. Preferred Catalyst Electrode: The electroconductive microparticles contained in the support of catalyst electrode, is carbon microparticles. The catalyst electrode further contains organic proton-conductive polymer.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The total amount of Lewis' acid property metal alkoxide and silicon oxide precursor in the proton conductor is 50-400 mol parts with respect to 100 mol parts of phosphoric acid compound. The amount of metal alkoxide in proton conductor is 5-50 mol parts with respect to 100 mol parts of silicon oxide precursor. The Lewis' acid property metal alkoxide contains titanium, aluminum or zirconium as Lewis' acid property metal. The silicon oxide precursor is alkoxide compound of silicon having proton dissociative group and alkoxide compound of silicon without having proton dissociative group. The proton dissociative functional group in alkoxide compound of silicon, is chosen from sulfonic acid group, phosphonic acid group, sulfonamide group, sulfonimide group and their derivatives. Preferred Catalyst Electrode: The electroconductive microparticles contained in the support of catalyst electrode, is carbon microparticles. The catalyst electrode further contains organic proton-conductive polymer.    TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The proton conductor contains organic proton-conductive polymer (20-80 weight %). The organic proton-conductive polymer has proton dissociative group at the side-chain terminal. The proton dissociative group is chosen from sulfonic acid group, phosphonic acid group, sulfonamide group, sulfonimide group and their derivatives.