Provided is a cathode active material for a lithium ion secondary battery in which the secondary particles constituting the powder have a high breaking strength and a good coatability, and a method for manufacturing same. The cathode active material for a lithium ion secondary battery includes a primary particle of a lithium composite compound; and secondary particles formed by an aggregation of primary particles, wherein a ratio between an average particle size of the primary particles and an average particle size of the secondary particles is 0.006 or more and 0.25 or less, an amount of lithium carbonate is 0.4% by mass or less, and a breaking strength of the secondary particles is 30 MPa or more.