The overall purpose of this study was to investigate the effects of level of isoflavones supplementation on bone metabolism in osteoporosis rats. The effects of level of isoflavones supplementation on calcium and osteocalcin blood level, femur/body weight, bone mineral density(BMD) and bone strength were inspected in this study. This study classified 28 of 12 weeks-old male Sprague Dawley rats which have osteoporosis caused by ovariectomy into four groups of 7 rats and made the subjects medicated them isoflavone. Group I was non-treatment after osteoporosis(control); Group II was low-dose isoflavone(20 mg/kg) feeding after osteoporosis; Group III was middle-dose isoflavone(40 mg/kg) feeding after osteoporosis; Group IV was high-dose isoflavone(80 mg/kg) feeding after osteoporosis; In the calcium and osteocalcin level as one of bone formation indexes, there was a statistically significant difference between the group II, III, IV compared to group I. In respect to the femur/body weight, there was a statistically significant difference between the group II, III, IV compared to group I. In the bone mineral density and bone strength test, there was a statistically significant difference between the group II, III, IV compared to group I. The above results suggests that isoflavone medicated is effective to prevention and treatment of osteoporosis.