Provided is a method for manufacturing a cathode active material for a lithium secondary battery, the method including heat-treating a precursor aqueous solution containing a lithium precursor, a transition metal precursor, and an organic acid containing a carboxyl group, and having a chelation index (C.I) value less than 1 and 0.5 or more, wherein the chelation index value is defined by transmittance of a peak located in a wavenumber from 1,700 to 1,710 cm -1 and transmittance of a peak located in a wavenumber from 1,550 to 1,610 cm -1 in Fourier transform infrared (FTIR) spectroscopy spectrum.