A process for producing a polymer electrolyte for a nonaqueous battery by introducing 80 to 97 wt. % of vinylidene fluoride monomer and 3 to 20 wt % of at least one monomer copolymerizable with vinylidene fluoride monomer simultaneously all at once into a polymerization vessel, polymerizing the monomers to provide a vinylidene fluoride copolymer having polymerized units of the monomers and having an inherent viscosity of 1.5 to 10 dl/g, and impregnating the vinylidene fluoride copolymer with a nonaqueous electrolytic solution to provide a polymer electrolyte.