PROBLEM TO BE SOLVED: To provide a method for treating osteoporosis using PTH that is highly safe and has high effect/efficacy, to provide a method for inhibiting/preventing bone fracture using PTH that is highly safe, and a medicinal agent for use in each of the aforementioned methods.SOLUTION: Specifically disclosed is a medicinal agent comprising PTH as an active ingredient, which is characterized in that PTH is administered once a week at a unit dose of 100 to 200 units in each of the aforementioned methods.【課題】安全性に優れ、かつ、効果・効能の高いPTHによる骨粗鬆症治療法の提供。安全性に優れたPTHによる骨折抑制/予防方法の提供。および、そのための薬剤の提供。【解決手段】上記の方法において、1回当たり100~200単位のPTHが隔週投与されることを特徴とするとする、PTHを有効成分として含有する薬剤。【選択図】なし