A positive electrode active material for a secondary battery is provided, which includes a lithium composite transition metal oxide including nickel (Ni), cobalt (Co), and manganese (Mn), wherein a particle of the lithium composite transition metal oxide includes a core portion and a resistance portion formed on a surface of the core portion, and is composed of a single particle, wherein the core portion has a layered crystal structure of space group R-3m, and the resistance portion has a cubic rock-salt structure of space group Fm-3m.