NOVELTY - A fluorine-containing proton exchange membrane comprises functional fluororesin and perfluorosulfonic acid resin (I), (II), (III) or (IV).    USE - Fluorine-containing proton exchange membrane is used for fuel cell.    ADVANTAGE - The fluorine-containing proton exchange membrane has excellent proton conductivity and mechanical stability, and prevents penetration of reaction medium effectively.    DETAILED DESCRIPTION - A fluorine-containing proton exchange membrane comprises functional fluororesin and perfluorosulfonic acid resin of formula (I), (II), (III), or (IV).    A=group of formula (a);    B'=group of formula (b);    M,M'=cerium, manganese, lanthanum, zinc, tungsten, titanium, vanadium, chromium, iron, cobalt, nickel, copper, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, tantalum, rhenium, iridium, platinum, sodium or potassium;    n,m=metallic values;    a,b=1 or more;    c,d,a',b',c',d'=0 or 1;    c+d,c'+d'=integer other than 0;    (a+b)/(a+b+c+d)=0.5-0.99;    (c+d)/(a+b+c+d)=0.01-0.5;    f,f',f"=2, 3 or 4;    g=3 or 4;    h=2 or 4;    i-l=1-10;    a'+b'=0 or more;    y=0.01-0.3 mole%;    x=99.7-99.99 mole%;    g',g"=2 or 3;and    h',h"=3 or 4.    An INDEPENDENT CLAIM is included for preparation of the fluorine-containing proton exchange membrane, which involves dissolving functional fluororesin in solvent, to obtain functional fluororesin solution (1-30 weight%), dissolving perfluorosulfonic acid resin in solvent, to obtain a perfluorosulfonic acid resin solution (1-30 weight%), mixing the obtained solutions, to obtaining a membrane solution (A), or dissolving functional fluororesin and perfluorosulfonic acid resin in solvent to obtain a membrane solution (B), casting, spray-coating or injection molding the obtained membrane solution (A) or membrane solution (B), to form a functional fluororesin single-layer membrane or fusing and extruding functional fluororesin comprising fluorosulfonic group, to form membrane, casting, spray-coating or injection molding the obtained perfluorosulfonic acid resin solution, to obtain a perfluorosulfonic acid resin single-layer membrane, providing perfluorosulfonic acid resin single-layer membrane as an intermediate layer, hot-pressing the perfluorosulfonic acid resin single-layer membrane on surface(s) of intermediate layer, to form a composite structure of fluorine-containing proton exchange membrane or forming membrane with functional fluororesin solution on surface(s) of intermediate layer through casting, spray-coating or injection molding, to form a composite structure of fluorine-containing proton exchange membrane or forming membrane with membrane forming solution (A) or (B) on surface(s) of intermediate layer through casting, spray-coating or injection molding, to form a composite structure of fluorine-containing proton exchange membrane.