Method Of Preparing Positive Electrode Active Material

The method of preparing a positive electrode capable of reducing the usage amount of a rinsing solution, and minimizing the surface degradation of a positive electrode active material is provided. A method of preparing a positive electrode active material includes: (A) preparing a lithium transition metal oxide; and (B) mixing the lithium transition metal oxide and a rinsing solution and performing rinsing and drying, wherein the rinsing solution includes one or more additive of LiOH, NaOH, or KOH, the additive is included in an amount of 3,000 ppm to 18,000 ppm relative to the lithium transition metal oxide in the rinsing solution, and the rinsing solution has a pH of 12 or more.