Agent prophylactique/thérapeutique contenant du Pth pour l'ostéoporose, caractérisé en ce que le Pth est administré une fois par semaine à dose unitaire de 100 à 200 unités
[Object] To provide a method of treating osteoporosis by PTH that has excellent safety and high efficacy. To provide a method for inhibiting/preventing bone fractures by PTH that has excellent safety. And to provide a drug to do this. [Means of Achievement] A drug containing PTH as the active ingredient, characterized in that a unit dose of PTH of 100 to 200 units is administered weekly in the above method.