The present invention relates to a non-aqueous electrolytic solution for a lithium secondary battery and a lithium secondary battery containing said solution. The non-aqueous electrolytic solution for the lithium secondary battery comprises a lithium salt, an organic solvent, a specific siloxane compound and a sulfonate compound. By addition of said specific siloxane compound, the non-aqueous electrolytic solution of the present invention reduces capacity problems caused by prolonged use of conventional lithium secondary batteries containing a non-aqueous electrolytic, and can therefore be especially useful for high capacity batteries.