NOVELTY - A lithium secondary battery (101) comprises a positive electrode (120) containing positive electrode active material layer (103), a negative electrode (121) containing negative electrode active material layer in which lithium ions are intercalated and from which intercalated lithium ions are discharged, and an ion conductor arranged between the positive electrode and the negative electrode and having lithium-ion conductivity. The positive electrode active material layer comprises lithium cobaltate and has alpha -sodium iron oxide-type crystal structure.    USE - Lithium secondary battery is used for main power supply of mobile battery apparatus and power tool, electric vehicle and motor vehicle.    ADVANTAGE - The lithium secondary battery has excellent cycle characteristics and reliability.    DETAILED DESCRIPTION - A lithium secondary battery comprises a positive electrode containing positive electrode active material layer, a negative electrode containing negative electrode active material layer in which lithium ions are intercalated and from which intercalated lithium ions are discharged, and an ion conductor arranged between the positive electrode and the negative electrode and having lithium-ion conductivity. The positive electrode active material layer comprises lithium cobaltate and has alpha -sodium iron oxide-type crystal structure. When two axes parallel to main surface of the positive electrode active material layer are provided as x-axis and y-axis, and axis perpendicular to main surface is provided as z-axis, the positive electrode active material layer is configured only of region (103a) in which (110) plane is oriented, and region (103b) in which (018) plane is oriented. The region (103a) and region (103b) are mixed in xy plane in the positive electrode active material layer.    DESCRIPTION OF DRAWING(S) - The drawing shows a cross-sectional view of lithium secondary battery.    Lithium secondary battery (101)    Positive electrode active material layer (103)    Positive electrode (120)    Negative electrode (121)    Regions (130a,130b)