The present disclosure relates to a polymer electrolyte membrane having a construction wherein an ionomer is charged in pores of a nanoweb having a high melting point, being insoluble in an organic solvent and having excellent pore characteristics, under optimum conditions. Therefore, an overall thickness of the electrolyte membrane may be reduced, thereby attaining advantages such as decrease in ohmic loss, reduction of material costs, excellent heat resistance, low thickness expansion rate which in turn prevents proton conductivity from being deteriorated over a long term. The polymer electrolyte membrane of the present invention comprises a porous nanoweb having a melting point of 300□ or more and being insoluble in an organic solvent of NMP, DMF, DMA, or DMSO at room temperature; and an ionomer which is charged in pores of the porous nanoweb and contains a hydrocarbon material soluble in the organic solvent at room temperature.