A nonaqueous electrolyte secondary battery comprising a positive electrode containing a positive active material, a negative electrode containing a negative active material and a nonaqueous electrolyte, wherein a lithium transition metal complex oxide A formed by allowing LiCoO.sub.2 to contain at least both of Zr and Mg and a lithium transition metal complex oxide B having a layered structure and containing at least both of Mn and Ni as transition metals and containing molybdenum (Mo) are mixed and used as said positive active material.