Provided is a lithium secondary battery including: a positive electrode plate that is a lithium complex oxide sintered plate with a thickness of 50 μm or more; a negative electrode plate; a separator interposed therebetween; and an electrolytic solution. The sintered plate has a structure in which primary grains having a layered rock-salt structure are bound to each other, the lithium complex oxide has a composition represented by Lix(Co1-yMy)O2±δ, wherein 1.0≤x≤1.1, 0