A carbon material and a method of manufacturing the carbon material are provided. By affixing diamond particles onto a carbonaceous substrate in a condition in which etching caused by hydrogen radicals is unlikely to occur, the substrate etching rate can be suppressed, and the carbon material is allowed to have a diamond thin film having excellent adhesion capability. The carbon material has a carbonaceous substrate showing a weight decrease under a diamond synthesis condition, diamond particles disposed on a surface of the carbonaceous substrate, and a diamond layer having the diamond particles as seeds. The weight of the diamond particles per unit area is set to from 1.0×10−4 g/cm2 to less than 3.0×10−3 g/cm2.