Vulnerability to toxic alien prey varies among native predator species, depending on their toxin resistance. Although foraging traits relating to ingestion rate of toxic substances are also likely to influence the predator vulnerability, they remain unexplored. To address this issue, we investigated the toxic impacts of an alien prey species (Bufo japonicus toad larvae) on two native amphibian species which are categorized in distinct functional groups (carnivore Hynobius retardatus salamander larvae and omnivore Rana pirica frog larvae). Through a series of indoor experiments, we found that frog larvae were particularly impacted, due to their lower toxin resistance and their higher ingestion rate of toxic substances. Specifically, omnivorous traits of frog larvae (i.e., food sharing and carcass consumption) rendered them more vulnerable compared to carnivorous salamander larvae. This is the first study suggesting that foraging traits of predators associated with their functional group (omnivore vs. carnivore) largely determine their vulnerability to toxic alien prey. By investigating such ecological traits we can begin to understand what types of predators are threatened by toxic alien prey. Regarding our system, our findings raise concerns about the toad invasion in Hokkaido and prompt us to investigate its potential impacts on native fauna in invaded areas.