A method of preparing a positive active material for a lithium secondary battery represented by the following Chemical Formula 1 (LiwNixCoyMn1-x-y-zMzO2) includes: (a) preparing a metal salt aqueous solution including a lithium raw material, a manganese raw material, a nickel raw material, and a cobalt raw material; (b) wet-pulverizing the metal salt aqueous solution using beads having a particle diameter of 0.05 to 0.30 mm at 2000 to 6000 rpm for 2 to 12 hours to prepare a slurry; (c) adding a carbon source to the slurry; (d) spray-drying the slurry of the step (c) to prepare a mixed powder; and (e) heat-treating the mixed powder.