BMD is prescribed by the balance of bone resorption and osteogenesis. In osteoporosis, this balance collapses according to a certain cause, bone loss starts as a result because bone resorption exceeds osteogenesis. Since a bone turnover marker shows the bone metabolism at the time of measurement quantitatively, it is thought that the change in BMD is reflected. Therefore, it is in predicting bone reduction of the future and fast bone loser identifying is expected by measuring bone turnover markers. Reduction of bone density is large in high turnover of bone metabolism, and it is shown clearly by recent research that the risk of fracture goes up. There is the necessity for evaluation of the bone turnover markers which made fracture the end point also in Japan.