A solid polymer electrolyte membrane that exhibits stable energy generation performance for a long period of time at an operation temperature of about 100° C. to about 300° C. in an unhumidified condition or a relative humidity of about 50%. A method for manufacturing the solid polymer electrolyte membrane and a fuel cell that uses the solid polymer electrolyte membrane are provided. The solid polymer electrolyte membrane comprises a polymer compound that has a side chain that includes a unit represented by Formula (a) that is formed at a heterocyclic nitrogen atom of a polybenzimidazole.