The home rang–body size allometry (HR ~ a x BW^b) has been observed in widespread taxa with various exponents. Although the trophic guild, the locomotion strategy, and the habitat dimension are listed for influential factors of the exponent (b), the mechanistic pathway of those factors is still unanswered. This study focuses on the herbivore–carnivore interaction in mammals because b distinctly differs between them and the ecological information about their interaction is relatively rich. The b for herbivores (0.87) was close to the b (0.75) in the metabolic rate–body size allometry. Therefore, the home range size can be interpreted as the proxy of the energy requirement. The b for carnivores (1.35) was much higher than that for herbivores. Since carnivores take herbivores, the b of carnivores could be transformed from that of herbivores, by taking the body size relationship between carnivores and herbivores and the recovery time of herbivore populations from predation. This transformation provided a reasonable exponent (1.34) for carnivores.