Police said on Friday that he was among a group of men who caught five amphibians at a reservoir near the city of Daejeon in March.
Believing the animals were bullfrogs, the men cooked and ate them at a restaurant days later.
The 57-year-old man began vomiting soon after and was rushed to a hospital, where he died the next morning.
Police said bufotenin, a chemical commonly found in toad toxin, was found in the leftovers of the meal.
