NOVELTY - A mixed solvent is prepared by adding cyclic carbonate and linear carbonate at less then 30 degrees C. A lithium salt is added as supporting electrolyte to the mixed solvent at same temperature. The obtained mixture has concentration of 0.2-3 mol with respect to 1 liter of non-aqueous electrolyte. Then, 50 g of aryl-alkyl group containing oxidation-decomposition preventing compound (1) is dissolved in the mixture, with respect to 1 kg of non-aqueous electrolyte. Thus, manufacture of non-aqueous electrolyte is carried out.    USE - Manufacture of non-aqueous electrolyte used for non-aqueous electrolyte secondary battery such as lithium secondary battery (claimed). Uses of the battery include but are not limited to portable video recorder with a built-in monitor, movie camera with a built-in monitor, compact camera, single-lens reflex camera, disposable camera, notebook computer, notebook-type word processor, electronic notebook, mobile telephone, cordless telephone, mustached skid, power tool, electrically-driven mixer and motor vehicles.    ADVANTAGE - The method provides non-aqueous electrolyte. The lithium secondary battery comprising the non-aqueous electrolyte has excellent capacitance, cyclic property and has few falls of discharge capacitance during repeated charging-discharging process.    DETAILED DESCRIPTION - A mixed solvent is prepared by adding cyclic carbonate and linear carbonate at less then 30 degrees C. A lithium salt is added as supporting electrolyte to the mixed solvent at same temperature. The obtained mixture has concentration of 0.2-3 mol with respect to 1 liter of non-aqueous electrolyte. Then, 50 g of aryl-alkyl group containing oxidation-decomposition preventing compound of formula (1) is dissolved in the mixture, with respect to 1 kg of non-aqueous electrolyte. Thus, manufacture of non-aqueous electrolyte is carried out. The aryl-alkyl group containing oxidation-decomposition preventing compound is of formula: R11-C(H)(R12)-R13.    R11=6-24C (un)substituted aryl;and    R12,R13=1-24C (un)substituted alkyl having electron donor group.    R11,R12 and R13 optionally combine to form a ring.