An electrolyte for nonaqueous electrolyte cells, which contains a nonaqueous organic solvent and a solute, the electrolyte for nonaqueous electrolyte cells being 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 wherein a countercation of the first compound group is at least one countercation selected from the group consisting of lithium ion, sodium ion, potassium ion, and tetraalkylammonium ion, and at least one compound selected from a second compound group consisting of a sulfonate group-containing imide salt, which is represented by the following general formula, M[R 1 OSO 2 NSO 2 OR 2] n wherein each of R 1 and R 2 independently represents at least one organic group selected from a C 1-10 straight chain or branched alkyl group or alkenyl group, a C 3-10 cycloalkyl group or cycloalkenyl group, and a C 6-10 aryl group, a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group, M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and n represents an integer equal to valence of the corresponding cation, and a phosphoryl group-containing imide salt represented by the following general formula, M[R 3 R 4 OPNPOR 5 R 6] m wherein each of R 3, R 4, R 5 and R 6 independently represents chlorine, fluorine or an organic group represented by -OF 7; and R 7 represents at least one organic group selected from a C 1-10 straight chain or branched alkyl group or alkenyl group, a C 3-10 cycloalkyl group or cycloalkenyl group, and a C 6-10 aryl group, a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group, M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and m represents an integer equal to valence of the corresponding cation, characterized in that addition of the first compound group is in a range of 0.01-5.0 mass % relative to the electrolyte for nonaqueous electrolyte cells, and characterized in that addition of the second compound group is in a range of 0.01-10.0 mass % relative to the electrolyte for nonaqueous electrolyte cells. 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 wherein a countercation of the first compound group is at least one countercation selected from the group consisting of lithium ion, sodium ion, potassium ion, and tetraalkylammonium ion, and at least one compound selected from a second compound group consisting of a sulfonate group-containing imide salt, which is represented by the following general formula, M[R 1 OSO 2 NSO 2 OR 2] n wherein each of R 1 and R 2 independently represents at least one organic group selected from a C 1-10 straight chain or branched alkyl group or alkenyl group, a C 3-10 cycloalkyl group or cycloalkenyl group, and a C 6-10 aryl group, a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group, M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and n represents an integer equal to valence of the corresponding cation, and a phosphoryl group-containing imide salt represented by the following general formula, M[R 3 R 4 OPNPOR 5 R 6] m wherein each of R 3, R 4, R 5 and R 6 independently represents chlorine, fluorine or an organic group represented by -OF 7; and R 7 represents at least one organic group selected from a C 1-10 straight chain or branched alkyl group or alkenyl group, a C 3-10 cycloalkyl group or cycloalkenyl group, and a C 6-10 aryl group, a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group, M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and m represents an integer equal to valence of the corresponding cation, characterized in that addition of the first compound group is in a range of 0.01-5.0 mass % relative to the electrolyte for nonaqueous electrolyte cells, and characterized in that addition of the second compound group is in a range of 0.01-10.0 mass % relative to the electrolyte for nonaqueous electrolyte cells. wherein each of R 1 and R 2 independently represents at least one organic group selected from a C 1-10 straight chain or branched alkyl group or alkenyl group, a C 3-10 cycloalkyl group or cycloalkenyl group, and a C 6-10 aryl group, a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group, M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and n represents an integer equal to valence of the corresponding cation, and a phosphoryl group-containing imide salt represented by the following general formula, wherein each of R 3, R 4, R 5 and R 6 independently represents chlorine, fluorine or an organic group represented by -OF 7; and R 7 represents at least one organic group selected from a C 1-10 straight chain or branched alkyl group or alkenyl group, a C 3-10 cycloalkyl group or cycloalkenyl group, and a C 6-10 aryl group, a fluorine atom, an oxygen atom, and/or an unsaturated bond may exist in the organic group, M represents an alkali metal cation, an alkali earth metal cation or an onium cation, and m represents an integer equal to valence of the corresponding cation,