NOVELTY - Manufacturing a highly-hydrophilized carrier, involves introducing a functional group functioning as a polymerization initiator to surface of a carbon carrier having pores; introducing an electrolyte monomer or its precursor; polymerizing the electrolyte monomer or its precursor to the polymerization initiator as a starting point; and hydrolyzing at least part of the polymerized polyelectrolyte by a strong alkali.    USE - For manufacturing highly hydrophilized carrier for manufacturing fuel-cell electrode (claimed) useful in polymer electrolyte fuel cell for mobile vehicles such as electric vehicle.    ADVANTAGE - The method improves catalytic efficiency by sufficiently assuring the three-phase interface, in which reactant gas, catalyst, and electrolyte meet in a carbon. Thus, electrode reaction is effectively facilitated thus improving fuel-cell electrical efficiency. Since at lease part of the polyelectrolyte is hydrolyzed by a strong alkali, physical and electrical contacts between highly hydrophilized carriers are facilitated, thus improving the electrical conductivity of the catalyst-supporting carriers as a whole. The fuel-cell electrode obtained by the method improves catalyst utilization. Since the catalyst that is submerged deep in carbon nano-pores forms part of the three-phase interface, existing catalyst can be used for reaction without waste. Thus, since an electrolyte monomer in a monomer state and a catalyst carrier are mixed and then polymerized by polymerization, ion-exchange paths are formed in the pores of the carrier, thereby improving catalyst utilization and electrical efficiency, even when the quantity of material is the same. Since at least part of the polyelectrolyte is hydrolyzed by a strong alkali, even in the presence of the above polyelectrolyte, physical and electrical contacts between catalyst carriers are facilitated, thus significantly improving the electrical conductivity of the catalyst carriers as a whole. Thus, electrical efficiency is improved. The method reduces quantity of inactive catalyst that is not in contact with the electrolyte.    DETAILED DESCRIPTION - Manufacturing a highly-hydrophilized carrier comprised of a carbon carrier and polyelectrolyte, involves introducing a functional group functioning as a polymerization initiator to the surface of a carbon carrier having pores; introducing an electrolyte monomer or an electrolyte monomer precursor; polymerizing the electrolyte monomer or the electrolyte monomer precursor to the polymerization initiator as a starting point; and hydrolyzing at least part of the polymerized polyelectrolyte by a strong alkali. The ratio of weight of the electrolyte to sum of weight of electrolyte and weight of catalyst-supporting carbon is less than 10% in step of polymerizing electrolyte monomer or electrolyte monomer precursor. The ratio of weight of the electrolyte to sum of weight of electrolyte and weight of the catalyst-supporting carbon is adjusted by the concentration of electrolyte monomer or concentration of electrolyte monomer precursor in the step of polymerizing electrolyte monomer or the electrolyte monomer precursor. The method further involves hydrolyzing the polymer or introducing an ion-exchange group, after the electrolyte monomer precursor is polymerized.    INDEPENDENT CLAIMS are included for the following:    (1) manufacturing a catalyst-supporting carrier involving allowing a carbon having pores to support catalyst; introducing a functional group functioning as a polymerization initiator to the surface and/or in the pores of the catalyst-supporting carbon; introducing an electrolyte monomer or its precursor; and polymerizing the electrolyte monomer or its precursor to the polymerization initiator; and hydrolyzing at least part of the polymerized polyelectrolyte by a strong alkali;    (2) manufacturing a fuel-cell electrode, involving use of catalyst-supporting carrier;    (3) a highly-hydrophilized carrier comprised of a carbon carrier and polyelectrolyte that exists on surface of a carbon having pores, and at least part of the polyelectrolyte is hydrolyzed by a strong alkali;    (4) a catalyst-supporting carrier comprised of a catalyst-supporting carbon and polyelectrolyte, where polyelectrolyte and catalyst exist on the surface of a carbon having pores and part of the polyelectrolyte is hydrolyzed by a strong alkali;    (5) a fuel-cell electrode comprising the catalyst-supporting carrier; and    (6) a polymer electrolyte fuel cell comprising an anode, a cathode, and a polymer electrolyte membrane disposed between the anode and the cathode, where the fuel-cell electrode is provided as the anode and/or the cathode.    DESCRIPTION OF DRAWING(S) - The figure shows the catalyst-supporting carrier composed of catalyst-supporting carbon and polyelectrolyte, in which the catalyst exists on the surface and/or in the pores of the carbon, and at least part of the polyelectrolyte is hydrolyzed by strong alkali.