Problem to be solved: to provide an inhibitor of osteoclast differentiation, a preventive agent for postmenopausal osteoporosis and an improvement agent, which is made of 10 - hydroxy-2-decenic acid as an active ingredient.The present inventors have found an effect of inhibiting osteoclast differentiation to 10-hydroxy-2-decenic acid as a result of an acute study, and the present invention has been completed.Diagram【課題】本発明は、１０－ヒドロキシ－２－デセン酸を有効成分とする、破骨細胞分化の抑制剤、閉経後骨粗鬆症予防・改善剤を提供することにある。【解決手段】本発明者らは、鋭意研究の結果、１０－ヒドロキシ－２－デセン酸に破骨細胞分化を抑制する作用を見出し、本発明を完成するのに至った。【選択図】図７
