disclosed is a polymer electrolyte membrane for a fuel cell that has a high ionic conductivity even at a high temperature without humidification . the polymer electrolyte membrane comprises a film composed of a polyimide copolymer containing phenylbenzimidazole , and an acid impregnated within the polyimide copolymer film . also disclosed is another polymer electrolyte membrane for a fuel cell that has good chemical resistance and improved physical properties when compared to those of the previous polymer electrolyte membrane .