Area-selective electroless deposition of gold nanostructures on a 6H-SiC substrate is demonstrated. Gold nanostructures selectively grow on a focused ion beam (FIB)-irradiated area on the 6H-SiC substrate when the substrate is exposed to a pure HAuCl4 aqueous solution. The nucleation of gold was more favorable on the Si face than on the C face. Quantitative evaluation of the amount of gold grown both on SiC and silicon is conducted to discuss the growth of gold, where silicon is a substrate we used in our previous study on this method. We reveal the mechanism of the growth of gold nanostructures as follows: Dangling bond defects formed in the FIB-irradiated area initiate the nucleation of gold by reducing Au ions in the solution at the surface. Once the SiC-gold or the silicon-gold boundary, which meets the Schottky contact condition, has formed, electrons in the non-FIB-irradiated region under/around the FIB-irradiated one also reduce Au ions on the gold surface through the boundary.