Provided is a cathode active material comprising a lithium composite oxide and a covering material which covers a surface of the lithium composite oxide. The lithium composite oxide is a multi-phase mixture including a first phase having a crystal structure which belongs to a monoclinic crystal; a second phase having a crystal structure which belongs to a hexagonal crystal; and a third phase having a crystal structure which belongs to a cubical crystal. The lithium composite oxide has an integral intensity ratio I(18°-20°)/I(43°-46°) of not less than 0.05 and not more than 0.99, where the integral intensity I(α°-β°) is an integral intensity of a peak which is a maximum peak present within a range of a diffraction angle 2θ of not less than α° and not more than β° in an X-ray diffraction pattern of the lithium composite oxide. The covering material has an electronic conductivity of not more than 106 S/m.