Method for manufacturing positive active material for lithium secondary battery

PURPOSE: A manufacturing method of a positive electrode active material is provided to effectively remove excessive lithium in manufacturing a positive electrode active material, thereby increasing sintering treatment amount. CONSTITUTION: A manufacturing method of a positive electrode active material comprises a step of a mixing a lithium raw material and a nickel composite compound and putting the mixture into a furnace; a step of sintering the put lithium raw material and nickel composite compound to manufacture a lithium composite oxide; and a step of cooling the lithium composite oxide. When cooling the manufactured lithium composite oxide, 0.3-10 volume% of carbon dioxide is put into the furnace. [Reference numerals] (AA) CO_2 content[vol%]