NOVELTY - A polymer electrolyte membrane for a fuel cell comprises: a hydrophilic channel formed in the polymer electrolyte membrane, with the polymer electrolyte membrane being proton-conductive; and a polymer micelle inside the hydrophilic channel of the proton-conductive polymer membrane, with the polymer micelle containing a vinyl-based polymer obtained from polymerization of vinyl-based monomers and an anionic surfactant surrounding the vinyl-based polymer.    USE - As a polymer electrolyte membrane useful in membrane-electrode assembly for a fuel cell and fuel cell system (claimed).    ADVANTAGE - The polymer electrolyte membrane has smaller, but more densely distributed internal channels to improve proton conductivity and to suppress cross-over of a fuel through the polymer electrolyte membrane; and includes polymer micelles inside a water ion cluster that thereby improve moisture retention and fuel cross-over inhibition properties.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) manufacturing a polymer electrolyte membrane, involving: preparing an emulsion polymerization solution by mixing a vinyl-based monomer, an anionic surfactant, and a radical polymerization initiator in water; dipping a proton-conductive polymer membrane in the emulsion polymerization solution to swell the membrane; and performing an emulsion polymerization of the monomer embedded inside the swelled proton-conductive polymer membrane to form a polymer micelle;    (2) a membrane-electrode assembly (A1) for a fuel cell, comprising: a polymer electrolyte membrane comprising a polymer micelle inside a hydrophilic channel of a proton-conductive polymer membrane, with the polymer micelle containing a vinyl-based polymer obtained from polymerization of vinyl-based monomers and an anionic surfactant surrounding the vinyl-based polymer; a cathode formed on one side of the polymer electrolyte membrane; and an anode formed on the other side of the polymer electrolyte membrane; and    (3) a fuel cell system, comprising: at least one electricity generating element, with the electricity generating containing the membrane-electrode assembly (A1), and separators disposed on both sides of the membrane-electrode assembly; a fuel supplier; and an oxidant supplier.