Method of Producing Positive Electrode Material for Secondary Battery

A method of producing a positive electrode material for a secondary battery includes preparing a lithium composite transition metal oxide containing nickel, cobalt, and manganese, forming a coating layer on a surface of the lithium composite transition metal oxide, and post-treating the lithium composite transition metal oxide having the coating layer formed thereon, wherein the post-treating is performed by exposing the lithium composite transition metal oxide having the coating layer formed thereon to moisture at a relative humidity of 10% to 50% at 25° C., and then heat treating the lithium composite transition metal oxide to remove residual moisture.