A composite material according to the present invention, is composed of SiC, SiO.sub.2, at least one out of Al and Si, with He leak rate of 1.3.times.10.sup.-10 Pam.sup.3/sec or below, thereby providing a composite material, which has a higher vacuum air-tightness, an excellent thermal conductivity, an adjustable coefficient of thermal expansion, small variation in strength and higher reliability, and a method for manufacturing the composite material, and a wafer holding member including the composite material.