PURPOSE: To improve the oxidation resistance of a carbon material by applying a B4C slurry to a part or total of the surface of a carbonaceous substrate, heat-treating the coated product and impregnating a heat-decomposed carbon into the heat-treated material.

CONSTITUTION: This carbon material coated with B4C and having excellent oxidation resistance can be produced by dispersing ≤3,000g of B4C powder having an average particle diameter of ≤50μm in 1 liter of water or an organic solvent such as alcohol to prepare a slurry, applying the B4C slurry to a part or total of the surface of a carbon substrate 11 by spraying or impregnating the slurry into the substrate by evacuation and pressing, evaporating the dispersion medium by heating or evacuation to form a layer of B4C particles 12 and depositing and impregnating heat-decomposed carbon 13 into the layer of the B4C particles 12 at a volume ratio (heat-decomposed carbon 13)/(B4C 12) of ≤1/2 (usually 1/20 to 1/10) by chemical vapor deposition process using a 1-8C hydrocarbon gas having a concentration of 3-30vol.% and diluted with H2 or Ar as the carbon generation source under a pressure of ≤100Torr at 800-2500°C (preferably 800-1300°C), thereby bonding the B4C particles with each other or B4C with the heat-decomposed carbon.