In an embodiment of the present invention, a positive active material for a lithium secondary battery is represented by Formula 1, and includes a core including a compound having a core portion and a surface portion, and the compound has a lower L3/L2 intensity ratio of Ni in the surface portion than an L3/L2 intensity ratio of Ni in the core portion. Li[LizA(1-z-a)Da]EbO2-b  [Formula 1] (In the above formula (1), A is NiαCoβMnγ, D is at least one element selected from the group consisting of Na, K, Mg, Ca, Sr, Ni, Co, Ti, Al, B, Si, Sn, Mn, Cr, Fe, V, Zr, Nb, and Mo, E is at least one element selected from the group consisting of P, F, and S, −0.05≤z≤0.1, 0≤a≤0.05, 0≤b≤0.05, 0.3≤α≤0.9, 0.05≤β≤0.4, and 0.05≤γ≤0.4.)(The L3/L2 intensity ratio of Ni is the oxidation number of Ni measured by electronic energy loss spectroscopy (EELS).).