A polymer electrolyte secondary cell that is superior in the cycle characteristic and security during cell overcharge is provided. The polymer electrolyte of the cell includes a non-aqueous solvent, a lithium salt, and a polymer. The non-aqueous solvent contains at least one of ethylene carbonate and propylene carbonate. The volume ratio (25° C., 1 atm) of the ethylene carbonate and the propylene carbonate combined to the non-aqueous solvent is equal to or more than 60%. The polymer is made of a copolymer having a monomer containing N,N-dimethyl acrylamide and a compound with three or more acrylate groups and/or methacrylate groups. The ratio of the compound to the total mass of the monomer is from 10 to 30 mass %. The ratio of the polymer to the polymer electrolyte is from 1.0 to 2.0 mass %.