In order to clarify the mechanism of mechanochemical polishing of SiC with Cr2O3abrasive, 6H‐wurtzite single‐crystal specimens were dry‐polished. A significant anisotropic polishing rate difference was found between Si(0001) and C(0001) surfaces. The C(0001) surface was removed 10 times as fast. Polished surfaces were observed from cross‐sectional and plan‐view directions by high‐voltage TEM. There was no trace of mechanical effects such as residual strain or scratches. The polishing debris was analyzed by X‐ray diffraction, high‐resolution TEM, and analytical TEM. No crystalline phases were identified from X‐ray diffraction patterns except for Cr2O3, while it was found from TEM observation that a large amount of an amorphous phase consisting of Si, C, and O was contained in the debris. These results indicated that the surface of SiC was removed mechanochemically by the aid of a catalytic oxidatio