Newly developed porous β-tricalcium phosphate composed of rod-shaped particles was grafted into distal end of the left femur of female Japan White rabbit. As a control, hydrixyapatite generated in the same size was grafted. In both implants, 350µm in diameter-sized holes were created vertically and horizontally. Three weeks after grafting, margin of the β-tricalcium phosphate was absorbed by osteoclasts and bone formation was seen near the absorbed region. Twenty-four weeks after grafting, more than 80% of the β-tricalcium phosphate was absorbed and newly formed bone was prominently observed. The hydroxyapatite was not remarkably absorbed even 24 weeks after grafting, and newly formed bone was observed only in the holes created in the implants. These results suggest that porous β-tricalcium phosphate composed of rod-shaped particles has highly biodegradable and osteoconductive nature, and appropriate to bone graft substitute.