Osteoporosis is a major public health issue in Japan, and key factors for its prevention are diet and exercise. Vitamin D and K are strongly associated with bone metabolism. The recommended daily vitamin D and K requirements are 400-800 IU and 250-300μg, respectively. In addition, exercise is effective for the improvement of bone mineral density in the elderly. Regular exercise and improvement of diet are important for the prevention of osteoporosis in the aging society.