POSITIVE ELECTRODE ACTIVE SUBSTANCE FOR NON-AQUEOUS ELECTROLYTE SECONDARY CELL, AND NON-AQUEOUS ELECTROLYTE SECONDARY CELL

A positive electrode active substance, wherein: the average primary particle diameter of an Ni-containing lithium complex oxide A is 0.5 μm or greater, and is greater than the average primary particle diameter (0.05 μm or greater) of an Ni-containing lithium complex oxide B; and the average secondary particle diameter of the Ni-containing lithium complex oxide A is 2-6 μm, and is less than the average secondary particle diameter (10-20 μm) of the Ni-containing lithium complex oxide B. The Ni-containing lithium complex oxides A, B contain 55 mol % or more of Ni relative to the total mol of metal elements excluding Li, have a crystallite diameter of 100-200 nm, and are such that the disorder of elemental Ni is 3% or less.