POSITIVE ELECTRODE ACTIVE MATERIAL FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERIES, AND NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

This positive electrode active material for nonaqueous electrolyte secondary batteries contains: a lithium transition metal composite oxide having secondary particles, each of which is formed of aggregated primary particles; and a surface modification layer which is formed on the surface of each primary particle of the lithium transition metal composite oxide. The lithium transition metal composite oxide contains at least Al and 80% by mole or more of Ni relative to the total number of moles of the metal elements excluding Li; and the surface modification layer contains at least Ba, and at least one of Sr and Ca.