The present invention is to provide a polymer electrolyte material realizing excellent proton conductivity even when it comes into direct contact with liquid fuel at high temperature and high concentration, and excellent fuel barrier property and mechanical strength, as well as to provide a polymer electrolyte fuel cell of high efficiency. A polymer electrolyte material of the present invention is characterized in that fraction Rw of non-freezing water shown by the equation (S1) below is 75 to 100% by weight, and an ionic group is included, in a moisture state taken out after 12-hour immersion in 1 to 30% by weight methanol aqueous solution at 40 to 80.degree. C. and then 24-hour immersion in pure water at 20.degree.: Rw=[Wnf/(Wfc+Wnf)].times.100 (S1) (wherein, Wnf represents an amount of non-freezing water per 1 g of dry weight of polymer electrolyte material, Wfc represents an amount of lower-melting point water per 1 g of dry weight of polymer electrolyte material). A polymer electrolyte part of the present invention is characterized by being made from such a polymer electrolyte material, a membrane electrode assembly of the present invention is characterized by being made from such a polymer electrolyte part, and a polymer electrolyte fuel cell of the present invention is formed by using by being made from such a membrane electrode assembly.