A positive electrode active material for a lithium ion secondary battery, the positive electrode active material comprising: lithium transition metal-containing composite oxide particles having a composition represented by general formula: Li 1+u Ni x Mn y Co z M1 t O 2, where -0.05 ≤ u ≤ 0.5, x + y + z + t = 1, 0.3 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.5, 0 ≤ t ≤ 0.1, and M1 is one or more additive elements selected from Mg, Al, Si, Ca, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, and a layered rock salt type crystal structure; and a coating layer present on at least a part of a surface of the lithium transition metal-containing composite oxide particles and formed of fine particles and/or a coating film of a metal composite oxide of Li and a metal element M2, where M2 represents one or more metal elements selected from Al, Ti, Zr, Nb, Mo, and W, the lithium transition metal-containing composite oxide particles including the coating layer having: a 50% cumulative diameter d50 of 3.0 μm or more and 7.0 μm or less, the 50% cumulative diameter d50 being a particle size at which a cumulative volume determined from a volume integrated value measured with a laser light diffraction scattering particle size analyzer is 50% of the total volume of all particles, a BET specific surface area of 2.0 m 2 /g or more and 5.0 m 2 /g or less, the BET specific surface area measured by a BET method using nitrogen gas absorption, a tap density of 1.0 g/cm 3 or more and 2.0 g/cm 3 or less, the tap density being a bulk density after a powder sample collected in a vessel is tapped 100 times according to JIS Z-2504, and an oil absorption amount of 30 ml/100 g or more and 60 ml/100 g or less, the oil absorption amount being measured using an oil absorption amount measuring apparatus in accordance with JIS K 6217-4: 2008, and the amount of M2 contained in the coating layer being 0.1 atom% or more and 1.5 atom% or less with respect to the total number of atoms of Ni, Mn, and Co contained in the lithium transition metal-containing composite oxide particles. lithium transition metal-containing composite oxide particles having a composition represented by general formula: Li 1+u Ni x Mn y Co z M1 t O 2, where -0.05 ≤ u ≤ 0.5, x + y + z + t = 1, 0.3 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.5, 0 ≤ t ≤ 0.1, and M1 is one or more additive elements selected from Mg, Al, Si, Ca, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W, and a layered rock salt type crystal structure; and a coating layer present on at least a part of a surface of the lithium transition metal-containing composite oxide particles and formed of fine particles and/or a coating film of a metal composite oxide of Li and a metal element M2, where M2 represents one or more metal elements selected from Al, Ti, Zr, Nb, Mo, and W, the lithium transition metal-containing composite oxide particles including the coating layer having: a 50% cumulative diameter d50 of 3.0 μm or more and 7.0 μm or less, the 50% cumulative diameter d50 being a particle size at which a cumulative volume determined from a volume integrated value measured with a laser light diffraction scattering particle size analyzer is 50% of the total volume of all particles, a BET specific surface area of 2.0 m 2 /g or more and 5.0 m 2 /g or less, the BET specific surface area measured by a BET method using nitrogen gas absorption, a tap density of 1.0 g/cm 3 or more and 2.0 g/cm 3 or less, the tap density being a bulk density after a powder sample collected in a vessel is tapped 100 times according to JIS Z-2504, and an oil absorption amount of 30 ml/100 g or more and 60 ml/100 g or less, the oil absorption amount being measured using an oil absorption amount measuring apparatus in accordance with JIS K 6217-4: 2008, and a 50% cumulative diameter d50 of 3.0 μm or more and 7.0 μm or less, the 50% cumulative diameter d50 being a particle size at which a cumulative volume determined from a volume integrated value measured with a laser light diffraction scattering particle size analyzer is 50% of the total volume of all particles, a BET specific surface area of 2.0 m 2 /g or more and 5.0 m 2 /g or less, the BET specific surface area measured by a BET method using nitrogen gas absorption, a tap density of 1.0 g/cm 3 or more and 2.0 g/cm 3 or less, the tap density being a bulk density after a powder sample collected in a vessel is tapped 100 times according to JIS Z-2504, and an oil absorption amount of 30 ml/100 g or more and 60 ml/100 g or less, the oil absorption amount being measured using an oil absorption amount measuring apparatus in accordance with JIS K 6217-4: 2008, and the amount of M2 contained in the coating layer being 0.1 atom% or more and 1.5 atom% or less with respect to the total number of atoms of Ni, Mn, and Co contained in the lithium transition metal-containing composite oxide particles.