A lithium secondary battery electrolyte comprising a non-aqueous solvent and a lithium salt dissolved therein, said electrolyte containing at least one compound having the formula (I) or (II): wherein, R1 and R2 independently indicate, a C1 to C12 alkyl group, a C3 to C6 cycloalkyl group, or an aryl group, x indicates an oxygen atom or a sulfur atom, and n indicates an integer of 1 or 2; R3—S—M  (II) wherein, R3 indicates a C1 to C15 alkyl group or a C3 to C12 cycloalkyl group which may be substituted with at least one C1 to C4 alkyl group, a C7 to C15 benzyl group which may be substituted with at least one C1 to C4 alkyl group, or a C6 to C15 aryl group, which may be substituted with at least one C1 to C4 alkyl group, M indicates an alkali metal, and R3 may be substituted with at least one halogen atom; and a lithium secondary battery using the same.