A 75-year-old man was admitted because of watery diarrhea, hematochezia and right lower abdominal pain. Many deep undermining colonic ulcers were found by colonoscopy, and we detected trophozoite amoeba pathologically. Metronidazole was administered orally from 3 days after admission. However, since CT demonstrated a huge abscess in the abdominal cavity, we performed percutaneous drainage from 17 days after admission. On day 157, the patient was discharged, because the colonic ulcers had almost healed, and trophozoite amoebas were not recognized pathologically.