Dislocation constraint in the growth of SiC crystal by the modified Lely method was studied. In SiC single crystal growth, the dislocations and defects generally propagate from the seed crystal surface. However, when the etch back on the seed crystal surface in the sublimation process was performed prior to growth, defects and dislocations propagation in the interface between the seed crystal and the grow'n crystal were reasonably suppressed. The switchover from the etch back to the growth could be performed without changing the heating condition during the initial process. We noticed that the density of the hollow defects called as micropipes in the grown crystal were decreased to 1/10 compared to that of the seed crystal used. We consider the etch back proccss of the seed crystal is an effective method for constraining the defects in the SiC crystal growth.