Disclosed is an electrolyte for nonaqueous electrolyte cells, which contains a nonaqueous organic solvent and a solute. This electrolyte is characterized by containing as additives at least one compound selected from a first compound group consisting of bis(oxalato)borate, difluoro(oxalato)borate, tris(oxalato)phosphate, difluorobis(oxalato)phosphate, and tetrafluoro(oxalato)phosphate, and at least one compound selected from a second compound group consisting of a sulfonate group-containing imide salt, which is represented by the general formula M[R1OSO2NSO2OR2]n, and a phosphoryl group-containing imide salt, which is represented by the general formula M[R3R4OPNPOR5R6]m. This electrolyte provides nonaqueous electrolyte cells with high-temperature durability without causing swelling and performance deterioration of batteries.