A positive electrode active material for nonaqueous electrolyte secondary batteries has a high charge/discharge capacity and produces high output, as well as has high filling ability. The positive electrode active material includes lithium-nickel composite oxide particles are formed by agglomeration of multiple primary particles, include pores, and have a layered crystal structure. The lithium-nickel composite oxide particles have an average particle size of 15 μm or more and 30 μm or less. The percentage of an area of the pores measured by a cross-sectional observation of the lithium-nickel composite oxide particles with respect to a cross-sectional area of the lithium-nickel composite oxide particles is 1.0% or more and 5.0% or less. A lithium-tungsten compound containing tungsten and lithium is present on the surface of and inside the secondary particles. The lithium-tungsten compound is present on at least part of the surface of the primary particles.