A material for medical application is required to have extended sustainability of mechanical strength together with fast bone replacement ability in human body. Composite material is preferred in the application because monolithic material does not meet the requirement. In this study, we have developed HAp/TCP composite. The mechanical property of the material is evaluated by the bending strength test. The bone replacement ability is evaluated by soaking the material in simulated body fluid (SBF). Measured result of concentration of Ca^<2+> ion in SBF indicated that the developed material has excellent bone replacement ability. The bending strength is maintained after I week of soaking in SBF due to precipitation of HAp on the surface proceeding to degrease of the strength at early stage of soaking due to dissolution of TCP.