We investigated the location of the nuclei of Shockley-type stacking faults (SSFs) in the 4H-SiC pin diodes, using electroluminescence (EL) imaging. The nuclei of SSFs were identified as three types, located (i) on the mesa edge, (ii) in the surface region, and (iii) inside the epilayer. We compared the frequency of the nuclei according to these three locations for the (0001) and (000-1) pin diodes. The number of SSFs originated from the nuclei inside the epilayer in the (000-1) pin diodes was much less (<4 cm-2) than that in the (0001) pin diodes. However, the numbers of SSF nuclei (0.3 ~ 0.8 per device) located on the mesa wall and the surface region in the (000-1) pin diodes were comparable to the (0001) pin diodes. We also investigated the process responsible for generating the SSF nuclei.