A battery electrolyte comprises: a non-aqueous solvent including a perfluoropolyether that is functionalized at only one molecule end, the perfluoropolyether including perfluoroalkyl chains and oxygen atoms in such a manner that a perfluoroalkyl chain and an oxygen atom are alternately bound to each other; and a metal salt that is a magnesium salt, an alkaline earth metal salt, or an alkali metal salt, and that is dissolved in the non-aqueous solvent.