Several kinds of biomaterials are known to possess osteoinductive ability without bone inductive substances in ectopic implantation. β-TCP is one such material that has been reported to exhibit this ability in a canine model. In addition, prostaglandin E2 has been proved to accelerate osteogenesis in a rodent model, and one of its receptors EP4 has been considered to play a particularly important role. We examined that the EP4 agonist accelerates β-TCP-induced osteoinduction in a canine model. The results suggested that the EP4 agonist accelerated not only osteoinduction but also osteoclastogenesis prior to bone formation.