PROBLEM TO BE SOLVED: To provide a method for inducing proliferation and differentiation of a cartilage cell or increasing cartilage substrate production by administering the effective dose of a RANKL binding molecule that acts on a cartilage precursor cell and/or a mesenchymal stem cell to promote cartilage differentiation, proliferation and maturity of these cells, reinforce the differentiation of the cartilage cell, and cause the proliferation of the cartilage cell; and a drug composition for inducing the proliferation and the differentiation of the cartilage cell or increasing the cartilage substrate production.SOLUTION: A drug composition for treating or preventing a cartilage metabolism disease includes a compound that acts on a cartilage precursor cell and/or a mesenchymal stem cell to cause at least one selected from among (a) promotion of differentiation of the cartilage precursor cell and/or the mesenchymal stem cell, (b) promotion of proliferation of the cartilage precursor cell and/or the mesenchymal stem cell, (c) promotion of maturity of the cartilage precursor cell and/or the mesenchymal stem cell, (d) reinforcement of differentiation of a cartilage cell, (e) proliferation of the cartilage cell and (f) an increase in cartilage substrate production as an active ingredient.【課題】軟骨前駆細胞及び/又は間葉系幹細胞に作用しそれらの細胞の軟骨分化、増殖、成熟を促進し、軟骨細胞分化を増強し、軟骨細胞の増殖を引き起こすRANKL結合分子を有効量投与することにより軟骨細胞の増殖・分化を誘導し、あるいは軟骨基質産生を増加させる方法及び軟骨細胞の増殖・分化を誘導し、あるいは軟骨基質産生を増加させるための医薬品組成物の提供。【解決手段】軟骨前駆細胞及び/又は間葉系幹細胞に作用し、(a) 軟骨前駆細胞及び/又は間葉系幹細胞の分化の促進、(b) 軟骨前駆細胞及び/又は間葉系幹細胞の増殖の促進、(c) 軟骨前駆細胞及び/又は間葉系幹細胞の成熟の促進、(d) 軟骨細胞分化の増強、(e) 軟骨細胞の増殖、並びに(f) 軟骨基質産生増加の少なくとも1つを引き起こす化合物を有効成分として含む、軟骨謝疾患の治療又は予防のための医薬組成物。【選択図】なし