Human serum albumin obtained by gene manipulation techniques can be purified by a combination of specified steps in which a culture supernatant obtained from a human serum albumin-producing host is subjected to ultrafiltration, heat treatment, acid treatment and another ultrafiltration, followed by subsequent treatments with a cation exchanger, a hydrophobic chromatography carrier and an anion exchanger, and by salting-out to thereby obtain a pure form of human serum albumin which contains substantially no proteinous and polysaccharide contaminants, which is formulated into a pharmaceutical preparation. The thus obtained human serum albumin can further be purified by treating recombinant human serum albumin with a hydrophobic chromatography carrier at pH of 2 to 5 and a salt concentration of 0.4 to 1 and exposing the carrier to a pH of 6 to 8 and a salt concentration of 0.01 to 0.3 M, or treating the culture supernatant with boric acid or a salt thereof at pH 8 to 11 for 1 to 10 hours and recovering the supernatant. This process makes it possible to effeciently purify recombinant human serum albumin and to provide substantially pure human serum albumin which does not contain producer host-related substances and other contaminants and is sufficiently free from coloration.