A positive active material including a compound represented by Li1+xM1−kMekO2. A surface part of a particle of the positive active material has a mole ratio [Me/M] (A) of element represented by Me to element represented by M in Li1+xM1−kMekO2 of 0.05≦A≦0.60; the entire particle has a mole ratio [Me/M] (B) of element represented by Me to element represented by M in Li1+xM1−kMekO2 of 0.003≦B≦0.012; and element represented by Me has a concentration difference of between two positions of less than or equal to about 0.02 wt % in an inner part of the particle.In Li1+xM1−kMekO2, −0.2≦x≦0.2, 0