A method according to the present invention for producing a cartilage-damage treatment agent, includes the steps of: (i) proliferating mesenchymal stem cells in a serum-free medium A containing an FGF, a PDGF, a TGF-², an HGF, an EGF, at least one phospholipid and at least one fatty acid； and (ii) mixing the mesenchymal stem cells thus proliferated in the step (i), an isotonic preserving agent, and a cytoprotective agent. This method provides a cartilage-damage treatment agent which favorably regenerates a cartilage tissue.
