Provided are a polymer electrolyte membrane used in fuel cells, and a method for producing the same, the method including a step of filling a crosslinkable ion conductor in the pores of a porous nanoweb support; and a step of crosslinking the ion conductor filled in the pores of the porous nanoweb support. The method for producing a polymer electrolyte membrane uses a relatively smaller amount of an organic solvent, can ameliorate defects of the support caused by solvent evaporation, and can enhance the impregnability of the ion conductor to the support and the convenience of the process.