NOVELTY - An all-solid-state lithium secondary battery (101) consists of a positive electrode (120) having positive electrode active material layer (103), a negative electrode (121), and a solid electrolyte layer (104). The positive electrode active material layer contains lithium cobaltate, and has ( alpha )-sodium-iron oxide-crystal structure. The solid electrolyte layer contains lithium lanthanum titanate, and has tetragonal crystal perovskite-type crystal structure. The positive electrode active material layer consists of a laminated structure having lower layer (103a) and upper layer (103b).    USE - All-solid-state lithium secondary battery is used as power supply of mobile apparatus, power tool, and electric vehicle.    ADVANTAGE - The all-solid-state lithium secondary battery has excellent charging/discharging cycle characteristics, output characteristics, and adhesiveness with respect to interface of positive electrode active material layer and solid electrolyte layer. The reduction of lithium conductivity due to crystal grain boundary is suppressed.    DETAILED DESCRIPTION - An all-solid-state lithium secondary battery consists of a positive electrode having positive electrode active material layer, a negative electrode having negative electrode active material layer (105) capable of inserting or discharging lithium ions, and a solid electrolyte layer arranged between positive electrode and negative electrode. The positive electrode active material layer contains lithium cobaltate, and has ( alpha )-sodium-iron oxide-crystal structure. The positive electrode active material layer consists of a laminated structure having lower layer and upper layer arranged between lower layer and solid electrolyte layer. The plane (110) is oriented in lower layer. The upper layer has a primary region (103b1), in which plane (110) is oriented, and a secondary region (103b2), in which plane (018) is oriented. The primary region and secondary region remain mixed in the positive electrode active material layer in plane (xy), when the axes parallel to the main surface of the positive electrode active material layer is maintained as x-axis and y-axis and an axis perpendicular to the main surface is maintained as z-axis. The solid electrolyte layer contains lithium lanthanum titanate, and has tetragonal crystal perovskite-type crystal structure. The plane (110) or plane (102) is oriented in the solid electrolyte layer.    DESCRIPTION OF DRAWING(S) - The drawing shows the cross-sectional view of all-solid-state lithium secondary battery and cross-sectional view of positive electrode active material layer.    All-solid-state lithium secondary battery (101)    Positive electrode active material layer (103)    Lower layer (103a)    Upper layer (103b)    Primary region (103b1)    Secondary region (103b2)    Solid electrolyte layer (104)    Negative electrode active material layer (105)    Positive electrode (120)    Negative electrode (121)