Provided is a lithium metal composite oxide having a layered structure, which is particularly excellent as a positive electrode active material for batteries that are mounted on electric vehicles or hybrid vehicles. Proposed is a lithium metal composite oxide having a layered structure, which is represented by general formula Li1+x(MnαCoβNiγ)1−xO2 (0.00≤X≤0.07, 0.10≤α≤0.40, 0.10≤β≤0.40, and 0.30≤γ≤0.75) and has a specific surface area of more than 2.0 m2/g but 5.0 m2/g or less and has an average particle size of the primary particles/crystallite size ratio of 5.7 to 18.5.