The present invention is to provide an electrolyte membrane for fuel cell of low fuel permeability and high proton conductivity and to provide a fuel cell comprising the electrolyte membrane.According to the present invention, a polymer membrane including repeating unit of five-membered heterocyclic rings is used as an electrolyte membrane of the fuel cell. The electrolyte membrane has high proton conductivity with free from moves of the fuel or water when the proton conducts in the electrolyte membrane.