Hydroxyapatite (HAp) sintered bodies with c axis orientation were fabricated using c axis oriented plate-like HAp aggregates synthesized as described by us. The results of scanning electron microscopy and X-ray diffractometry indicated that the plate-like HAp aggregates accumulated horizontally to the flat surfaces of the cylindrical HAp sintered bodies and the c axis orientation of the HAp crystals perpendicular to the wide surfaces of the aggregates were maintained even after sintering.