The effect of calcination on the mechanical properties of hydroxyapatite and zirconia composite (HAp:ZrO2= 30:70, 50:50, 70:30 mass%) was investigated. The calcination of ball-milled mixture in air at 900°C for 0, 2 and 4 hours increased the crystallinity. Then, it was assigned that the particles form of hydroxyapatite was changed from needle-like to sphere-like by calcination. The calcined mixture was sintered by spark plasma sintering (SPS) at 1200°C with a pressure of 40MPa for 5 minutes. The calcination process caused the enhancement of flexural strength of the composite.