Abstract: An object of the present invention is to provide a preventive drug and a therapeutic drug for diseases caused by abnormal bone metabolism, especially osteoporosis, which is more effective than conventional drugs. Combined use of N-hydroxy-4-{5-[4-(5-isopropyl-2-methyl-1,3-thiazol-4-yl)phenoxy]pentoxy}-benzamidine, or a salt thereof; and at least one compound selected from the group consisting of etidronic acid, clodronic acid, pamidronic acid, tiludronic acid, risedronic acid, minodronic acid, ibandronic acid, zoledronic acid, and salts thereof can exert higher bone resorption inhibitory effect and provide a preventive effect and a therapeutic effect for diseases caused by abnormal bone metabolism, especially osteoporosis as compared with administration of the respective agents respectively.