Nonaqueous cathode active material and a non-aqueous electrolyte secondary battery electrolyte secondary battery

Providing a cathode active material capable of improving the output characteristics of the nonaqueous electrolyte secondary battery. Nonaqueous positive electrode active material of electrolyte secondary battery 1 includes a first positive electrode active material, and a second cathode active material. The first cathode active material is cobalt content 15% or more in atomic percentage in the transition metal. Second cathode active material, the cobalt content is less than 5% in atomic percentage in the transition metal. The average secondary particle diameter r1 of the first cathode active material is less than the average secondary particle diameter r2 of the second cathode active material.