A positive electrode active material for a non-aqueous electrolyte secondary battery includes a particle of a composite oxide which contains Li and Co, wherein: the composite oxide further contains an element M.sup.1 and an element M.sup.2; the element M.sup.1 is at least one selected from the group consisting of Mg, Cu and Zn; the element M.sup.2 is at least one selected from the group consisting of Al, Ca, Ba, Sr, Y and Zr; the element M.sup.1 is uniformly distributed in the particle; and the element M.sup.2 is distributed in the surface portion of the particle more than in the inside thereof.