The invention provides a high purity carbonaceous material which is reduced in contents of oxygen, nitrogen and chlorine readily binding to carbon atoms and in contents of elements, phosphorus, sulfur and boron, readily binding to carbon atoms upon heating and which can be used in producing single crystals such as semiconductors, a high purity carbonaceous material for use as a substrate for ceramic layer coating, and a ceramic layer-coated high purity carbonaceous material. The high purity carbonaceous material has oxygen content of 1.times.10.sup.18 atoms/cm.sup.3 or less as determined by SIMS. Its chlorine content is preferably 1.times.10.sup.16 atoms/cm.sup.3 or less as determined by SIMS, and its nitrogen content is preferably 5.times.10.sup.18 atoms/cm.sup.3 or less as determined by SIMS. Its phosphorus, sulfur and boron contents are preferably not higher than respective specified values. Such a high purity carbonaceous material is coated with ceramic layer.