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

This positive electrode active material contains a lithium transition metal composite oxide that contains 85% by mole or more of Ni relative to the total number of moles of metal elements excluding Li. The lithium transition metal composite oxide contains at least one metal element M1 that is selected from among Mg, Ti, Nb, Zr and V in an amount of 3% by mole or less relative to the total number of moles of metal elements excluding Li. In addition, the ratio of the concentration of the metal element M1 contained in the shell of each primary particle of the composite oxide to the concentration of the metal element M1 contained in the core is from 1.01 to 20; and at least one metal element M2 that is selected from among Ca and Sr is present on the surface of each primary particle in an amount of 1% by mole or less relative to the total number of moles of metal elements excluding Li.