An exemplary lithium secondary battery includes: a positive electrode including a positive-electrode active substance layer 103; a negative electrode; and a solid electrolyte layer 104. The positive-electrode active substance layer 103 comprises lithium cobaltate, and has an α-NaFeO2 type crystal structure. The positive-electrode active substance layer 103 includes a lower layer 103a, and an upper layer 103b interposed between the lower layer and the solid electrolyte layer. The lower layer 103a is oriented in the (110) plane. The upper layer 103b is composed only of first regions 103b1 oriented in the (110) plane and second regions 103b2 oriented in the (018) plane, the first and second regions being mixedly present in the xy plane of the positive-electrode active substance layer. The solid electrolyte layer 104 comprises lithium lanthanum titanate, and has a tetragonal perovskite-type crystal structure. The solid electrolyte layer 104 is oriented in the (110) or (102) plane.