Abstract: The present invention relates to a method for preparing a culture medium containing exosomes released by umbilical cord blood stem cells. The preparation method is based on culturing the umbilical cord blood stem cells in a serum-free medium supplemented with GDF-11, EGF, FGF2, TFG-?1, and/or VEGF. The culture medium produced by treating umbilical cord blood stem cells with a serum-free medium supplemented with 5 types of growth factors and the exosomes isolated from the culture medium has a higher total protein content and extracellular matrix protein content, when compared to a culture medium produced by culturing umbilical cord blood stem cells in a serum-free medium to which the growth factor is not added. In addition, exosomes released by umbilical cord blood stem cells cultured in a serum-free medium containing five growth factors have a high concentration, a small size, and an even distribution.