The present invention herein discloses a method for purifying human serum albumin, which is characterized in that it comprises the steps of heat-treating a human serum albumin-containing solution including impurities originated from a host cell, in the presence of a divalent cation such as calcium ion, magnesium ion, nickel ion, cobalt ion, iron ion and zinc ion to thus selectively allow the impurities to undergo agglutination. The present invention also provides the highly purified human serum albumin prepared by the foregoing method.