The present invention relates to a lithium secondary battery comprising an overdischarge-preventing agent. Particularly, the present invention provides a lithium secondary battery comprising an overdischarge-preventing agent having superior effects for an overdischarge test and showing 90% or more capacity recovery after the test, by introducing lithium nickel oxide into a cathode for a lithium secondary battery comprising a lithium transition metal oxide capable of occluding and releasing lithium ions as an overdischarge-preventing agent to supply lithium ions such that irreversible capacity of an anode can be compensated or better, thereby lowering voltage of a cathode first to prevent voltage increase of an anode during the overdischarge test.