POSITIVE ELECTRODE ACTIVE MATERIAL FOR NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY AND METHOD FOR PRODUCING THE SAME, METHOD FOR EVALUATING POSITIVE ELECTRODE ACTIVE MATERIAL FOR NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY, AND NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY

A positive electrode active material for non-aqueous electrolyte secondary battery containing a lithium-nickel-manganese composite oxide formed of secondary particles with a plurality of aggregated primary particles, in which the positive electrode active material is represented by a general formula (1): LidNMnMNbcO, at least a part of niobium is solid-dissolved inside the primary particles, and an amount of lithium to be eluted into water when the positive electrode active material is immersed in water is 0.02% by mass or more and 0.10% by mass or less with respect to the entire positive electrode active material as determined by a neutralization titration method.