SiC wafers were characterized by X-ray topography at SPring-8. The topography of (11 (2) over bar3) and (1 (1) over bar 03) planes in a transmission mode changed largely. Stress field was relaxed by large defects such as sub-grain boundaries and cracks. And we observed other small defects, which have the different Burgers vectors of the sub-grain boundary and the edge dislocation.