Disclosed herein is a composition for the treatment of articular cartilage damage or loss or defect. The composition for the treatment of articular cartilage injury of the present invention includes (i) cellular components separated, proliferated, and/or differentiated from the umbilical cord blood, (ii) a culture medium; and (iii) a biocompatible polymer. The composition has very superior ability of proliferation and differentiation and easier to be collected and acquired.