This positive electrode active material comprises an Ni-containing lithium composite oxide A and an Ni-containing lithium composite oxide B. Each of the Ni-containing lithium composite oxide A and the Ni-containing lithium composite oxide B contains 50% by mole or more of Ni relative to the total number of moles of the metal elements excluding Li; the Ni-containing lithium composite oxide A has an average primary particle diameter of 2 μm or more, an average secondary particle diameter of from 2 μm to 6 μm, and a particle breaking load of 5 mN or more; and the Ni-containing lithium composite oxide B has an average primary particle diameter of 1 μm or less, an average secondary particle diameter of from 10 μm to 20 μm, and a particle breaking load of 20 mN or more, while having a coating layer on the surface of each primary particle.