With coming of aged society, male patients with osteoporosis are increasing, and it is important to prevent and treat them. In male osteoporosis, secondary osteoporosis is relatively common as an etiology, and therefore it is necessary to exclude secondary causes, when it will be diagnosed. In female a rapid decrease of bone mineral density (BMD) is observed after menopause, while in male such changes are not. Japanese Society of Bone and Mineral Research proposed diagnostic criteria of male osteoporosis, which 70% of young adult mean (YAM) of hip BMD was used as cut-off value for osteoporosis.