A generation mechanism of graphite particle inclusions in 6H-SiC single crystals grown by sublimation boule growth technique was investigated based upon HRTEM analysis. The one side of SiC/graphite interface that is perpendicular to [0001] had vicinal atomic step of 6H-SiC. At the opposite side of the interface, singular (0001) 6H-SiC and (0001) graphite contacted with identical crystal orientation. Graphite layers close to the singular interface showed well ordered crystal structure, while it was observed to be disturbed toward the vicinal interface. From EDX analysis, the disturbance of graphite layers particularly close to the vicinal interface was supposed to be due to the high concentration of silicon contained species. Generation mechanism of graphite particle inclusions in SiC single crystals proposed in the present research is that they generated through the dissociative evaporation of SiC from the vicinal step of SiC, and the simultaneous formation of graphite layers.