Provided is a polymer electrolyte membrane including an inorganic nanoparticle bonded with a proton-conducting group, a solid acid and a proton-conducting polymer. The inorganic nanoparticle bonded with the proton-conducting group may be obtained by reacting a compound including a proton-conducting group with a metal precursor. The polymer electrolyte membrane has significantly enhanced proton conductivity and reduced methanol crossover.