To provide a positive electrode active material for a non-aqueous electrolyte secondary battery, which if used as a positive electrode for a lithium ion secondary battery, the battery internal resistance can be reduced, giving a secondary battery superior in output characteristics and life property. After mixing raw material powders in specified quantities of each so as to become a lithium-metal complex oxide represented by Li.sub.zNi.sub.1-wM.sub.wO.sub.2 (wherein M is at least one kind or more of metal elements selected from the group consisting of Co, Al, Mg, Mn, Ti, Fe, Cu, Zn, and Ga; and w and z respectively satisfy 0