A culture medium containing human serum albumin obtained by genetic manipulations (rHSA); a method for culturing animal cells characterized by culturing the cells in the above-mentioned medium; and a process for producing a physiologically active substance characterized by culturing animal cells capable of producing the physiologically active substance in the above-mentioned medium and taking up the produced physiologically active substance from the culture. The use of rHSA with uniform qualities makes it possible to achieve the proliferation of the cells and the productivity of the physiologically active substance each comparable to those achieved by using a serum-containing medium and/or a conventional serum-free medium containing HSA originating in plasma while stabilizing the medium qualities and ensuring the reproducibility of the culture.