This study was carried out to investigate whether giant water bug, designated as an endangered species by the Ministry of Environment of Korea since 1997, can control American bull frog tadpole which has been designated as an Invasive Alien Species(IAS) by the Ministry of Environment of Korea since 1998. The experiment was conducted through food preference between fish (Crucian carp, Carassius auratus) and American bull frog tadpole(Rana catesbeiana) in laboratory condition (25±1°C) in HECRI. Potential food such as fish(weight: 8.2±0.6, length: 87.4± 1.6mm) and American bull frog tadpole(weight: 6.8±0.4g, length: 92.3±1.6mm) were inserted 5 individuals respectively in the nineteen acrylate cages with one pair of L. deyrollei simultaneously. Twice(10:00, 18:00) per a day was monitored. Once we confirmed prey was consumed by L. deyrollei, removed and replaced with same species to maintain same number immediately. Preference for American bull frog tadpole was significantly higher(93.6%) than fish(6.4%) (F=30.65, df=1, 18, P<0.0001).