Abstract: A composite ceramic body which includes three phases consisting of a MgO phase, a YAP (YAlO3) phase and a spinel (MgAl2O4) phase. This composite ceramic body has a plasma resistance greater than that of alumina and approximately equal to that of MgO. Mechanical properties, such as hardness and bending strength, of the composite ceramic body, are approximately equal or superior to those of Al2O3. A raw material cost and a manufacturing cost thereof are lower than those of a rare-earth oxide. Further, electric conductive particles may be added thereto to lower an electrical resistivity. The composite ceramic body is suitably usable as component parts for a semiconductor manufacturing equipment.