An electrolyte for a lithium secondary battery comprises a non-aqueous organic solvent including 20 to 95 vol % of an ester-based or ether-based organic solvent based on the total amount of organic solvent; lithium salts; and an additive compound having at least two carbonate groups. A lithium secondary battery including this electrolyte has good swelling inhibition properties as well as electrochemical properties such as capacity and cycle life.