The dependency of void shape on Si surface orientation was investigated in the growth of silicon carbide (SiC) films on Si substrates. The orientation of the SiC films followed that of the Si substrate. In the silicon side of the SiC/Si interface, reverse-triangle-shaped voids were observed for the growth of SiC(100) on Si(100), whereas trapezoid-shaped voids were observed for the growth of SiC(111). on Si(111). The origin of the voids seemed to be the oxygen-relative defects inherently existing in bulk Si wafers. The shape of the voids was determined by that of the etch pit initially formed during the hydrogen etching process, which depends on the orientation of the silicon substrate. The mechanism of the void formation in the growth of SiC films on Si substrates was proposed based on the experimental results.