Needle-like hydroxyapatites obtained through a hydration reaction process between anhydrous dicalcium phosphate (ADCP) and tetracalcium phosphate (TTCP) were reinforced with wheat starch to form composite blocks, and they showed mechanical properties corresponding to their compositions: mass fraction of calcium phosphate powders/starch solution and starch concentration. A kind of the composite granules was found to be osteoconductive in an in vivo examination with a rat model.