We studied the impact of the lower-layer vegetative structure on habitat selection by raccoon dog. First, we calculated“a plant biomass index” based on the area, sociability, and height of each vegetation unit of the lower layer, and determined the relationship between the distribution of lower-layer vegetation and the geographical features of the site. Next, we used radiotelemetry to evaluate environmental selectivity by raccoon dogs. We related the structure of the lower-layer vegetation to the habitat selected by the raccoon dogs. Our analysis revealed that the raccoon dogs had a significant preference for inclined ground with a high plant biomass index and a high occurrence of Pleioblatus chino. Thus, the structure of the lower-layer vegetation in a forest is as significant as the forest type in restricting the habitat of raccoon dogs.