A non-aqueous electrolyte comprising (i) a non-aqueous solvent, especially mainly composed of a cyclic carbonate and a cyclic ester and optionally a linear carbonate, and (ii) an electrolyte salt, especially LiBF4, dissolved therein and (iii) a vinyl sulfone derivative having the formula (I): wherein R indicates a C1 to C12 alkyl group, C2 to C12 alkenyl group, or C3 to C6 cycloalkyl, and also a lithium secondary battery using the same are disclosed.