We investigated the calcium bioavailability of milk calcium, taken with or without cheese. Twenty-four 6-week-old male rats for a meal-feeding experiment were trained to consume an AIN-76 diet within 2 h (2 times per day) for 2 weeks. The rats were then divided into three experimental groups, each fed 2 types of experimental diets: Control group, Cheese group, and Ca-Cheese group. The rats were each alternately given 2 types of experimental diets at 2-h meal-feeding for 31 days. The breaking force and energy of the femur in the Ca-Cheese group were significantly higher than in the control group. The bone mineral density (BMD) of the lumbar spine and the femur in the Ca-Cheese group was also significantly higher than in the other two groups. These results indicate that milk calcium taken with cheese increases bone strength and BMD efficiently, results that may be useful for the prevention of osteoporosis.