Disclosed in a positive active material for a lithium secondary battery including a compound represented by formula 1 and having a 10% to 70% ratio of diffracted intensity of diffraction lines in 2θ=53° (104 plane) with respect to diffracted intensity of diffraction lines in the vicinity of 2θ=22° (003 plane) in X-ray diffraction patterns using a CoKα-ray, LixCoO2-yAy  (1) wherein, x is from 0.90 to 1.04, y is from 0 to 0.5, and A is selected from the group consisting of F, S and P.