Provided are a cathode active material including lithium transition metal phosphate particles, wherein the lithium transition metal phosphate particles include a first secondary particle formed by agglomeration of two or more first primary particles, and a second secondary particle formed by agglomeration of two or more second primary particles in the first secondary particle, and a method of preparing the same. Since the cathode active material according to an embodiment of the present invention may include first primary particles and second primary particles having different average particle diameters, the exfoliation of the cathode active material from a cathode collector may be minimized and performance characteristics, such as high output characteristics and an increase in available capacity, of a secondary battery may be further improved. In addition, since the first secondary particles are porous, the secondary particles are collapsed and fractured due to rolling when used in a cathode. Thus, a spring
