Hydroxyapatite (HA) ceramic was prepared using tuna bone powders and was characterized on properties of sintered samples. The aim was to prepare dense and bulk HA sintered suitable for clinical applications. Thermal analysis, X-ray diffraction analysis, microscopic observation, and mechanical evaluation were applied to characterize sintered HA to find optimum processing condition. The major phase of sintered HA was observed up to 1300$^{C}$ and $eta$-TCP was observed as temperature increased. The density of sintered HA was increased up to 1350$^{C}$ and decreased with further increasing temperature. The flexural strength of sintered HA at 1350$^{C}$ showed 58 MPa as the highest value in this work. The results suggest that the crystal phase and transformation characteristics of HA prepared from tuna bone are the same as the behavior of HA powders made by chemical synthesis.