Provided are a cathode material for lithium ion secondary battery having excellent rate characteristics and cycle characteristics while a cathode active substance has high density, and a lithium ion secondary battery cathode and a lithium ion secondary battery that use the above cathode material. The cathode material for lithium ion secondary battery (1), represented by Li1+xM11−x−yM2yO2 [where −0.1≤x≤0.3, 0≤y≤0.1; M1 is Ni, Co, Mn; and M2 is Mg, Al, Ti, Zr, Mo, Nb, Fe, B], is an agglomerate including secondary particles (50, 60) both formed via aggregation of lithium metal composite oxide primary particles (10) having a layered structure. A mean porosity of the secondary particles having a particle size of more than 10 μm and equal to 50 μm or less is higher than that of the secondary particles having a particle size of 0.5 μm to 10 μm.