To increase safety against overcharging of a lithium secondary cell which uses a lithium-nickel compound oxide as a positive electrode active material. A lithium secondary cell comprises a casing (2,3) and a lithium secondary cell element (1) using a lithium-nickel compound oxide as a positive electrode active material, accommodated in the casing. The specific surface area of the lithium-nickel compound oxide is from 0.1 to 10 m²/g, and a surface area capacity ratio S/C, i.e. a ratio of a cell surface area S (cm²) to a cell capacity (mAh), is from 0.05 to 5.