It is intended to provide a bone resorption inhibitor which comprises, as the active ingredient, a barley extract obtained by extracting barley flour (milled barley) with water or a buffer solution, a fraction obtained by fractionating the barley extract or a product obtained by enzymatically treating the barley extract or fraction thereof as described above. Thus, a bone resorption inhibitor, which has a high safety for the human body, is applicable not only to drugs but to foods, shows a different mechanism from that of cathepsin K inhibitors and enables the prevention and amelioration (healing and relief) of bone diseases such as osteoporosis and rheumatoid arthritis, is provided.
