The novel bonding of an additional carbon layer over a C/C composite substrate surface was studied. Furan resin was selected for the additional carbon layer precursor. Molding was performed using a hot press apparatus. Polyvinyl chloride resin (PVC) was used as the bonding agent. The bonding mechanisms were studied with thermal gravity analysis, thermal gravity-mass spectroscopy, and high-temperature electron paramagnetic resonance spectroscopy. No peel-off was observed at the boundary between the carbon layer derived from furan resin/graphite powder and the C/C composite after loading by an external stress. The spins in thin carbon derived from PVC are recombined and are erased by the particular sites of graphite surface as one of roles of enhancement of adhesion.