Non-aqueous electrolyte secondary battery

In a non-aqueous electrolyte secondary battery provided with a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, a positive electrode active material is a mixture of lithium-manganese composite oxide and at least one of lithium-nickel composite oxide represented by a general formula LiNiM1Oand lithium-cobalt composite oxide represented by the general formula LiCoM2O, and said non-aqueous electrolyte solution contains at least a saturated cyclic carbonic acid ester and an unsaturated cyclic carbonic acid ester having double bond of carbon where content by amount of said unsaturated cyclic carbonic acid ester having double bond of carbon is in a range of 1.0 × 10to 2.4 × 10g per positive electrode capacity 1 mAh.