A method of preparing a cathode active material precursor for a lithium rechargeable battery, the method comprising: preparing a metallic salt aqueous solution for formation of a core part and a metallic salt aqueous solution for formation of a shell part that include nickel, cobalt, and manganese as metallic salts; providing a chelating agent, an alkaline aqueous solution, the metallic salt aqueous solution for the formation of the core part, and the metallic salt aqueous solution for the formation of the shell part into a reactor while changing a mixing ratio of the metallic salt aqueous solution for the formation of the core part and the metallic salt aqueous solution for the formation of the shell part, thereby forming a concentration gradient part of which concentrations of metallic salts are gradually changed; providing a chelating agent, an alkaline aqueous solution, the metallic salt aqueous solution for the formation of the core part, and the metallic salt aqueous solution for the formation of the shell part into the reactor while mixing the metallic salt aqueous solution for the formation of the core part and the metallic salt aqueous solution for the formation of the shell part at a fixed ratio, thereby forming a shell part having a fixed concentration; and drying and heating a formed precipitate to prepare an active material precursor, wherein a concentration of a specific metallic salt of the concentration gradient part in a contact portion of the concentration gradient part and the shell part is denoted by "M C ", and a concentration of the specific metallic salt of the shell part in the contact portion of the concentration gradient part and the shell part is denoted by "M S ", and wherein the M C and the M S satisfy a relation formula M C ≠M S. preparing a metallic salt aqueous solution for formation of a core part and a metallic salt aqueous solution for formation of a shell part that include nickel, cobalt, and manganese as metallic salts; providing a chelating agent, an alkaline aqueous solution, the metallic salt aqueous solution for the formation of the core part, and the metallic salt aqueous solution for the formation of the shell part into a reactor while changing a mixing ratio of the metallic salt aqueous solution for the formation of the core part and the metallic salt aqueous solution for the formation of the shell part, thereby forming a concentration gradient part of which concentrations of metallic salts are gradually changed; providing a chelating agent, an alkaline aqueous solution, the metallic salt aqueous solution for the formation of the core part, and the metallic salt aqueous solution for the formation of the shell part into the reactor while mixing the metallic salt aqueous solution for the formation of the core part and the metallic salt aqueous solution for the formation of the shell part at a fixed ratio, thereby forming a shell part having a fixed concentration; and drying and heating a formed precipitate to prepare an active material precursor, wherein a concentration of a specific metallic salt of the concentration gradient part in a contact portion of the concentration gradient part and the shell part is denoted by "M C ", and a concentration of the specific metallic salt of the shell part in the contact portion of the concentration gradient part and the shell part is denoted by "M S ", and wherein the M C and the M S satisfy a relation formula M C ≠M S.