A 40-year-old man sometimes complained of severe epigastric discomfort from one month ago. Duodenal ulcer was found by gastroduodenal endoscopy at the another clinic. So, he came to our hospital for detail examination. The gastroduodenal endoscopy showed irregular-shaped duodenal ulceration in the opposite side of the superior duodenal angle. The abdominal ultrasonography showed lymph node swelling around the hilus of the liver. The colonoscopy showed irregular-shaped ileocecal ulceration. The histological examination on biopsy specimen revealed epithelioid granuloma without caseous necrosis. Although the tubercle bacilli were not found by the culture examination, we suspected the duodenum and ileocecal tuberculosis. We started the antituberculotic therapy with isonicotinic acid hydrazide and rifampicin. After six months, the gastroduodenal endoscopy and colonoscopy revealed ulcer scar. The abdominal ultrasonography showed reduction of lymph node swelling. We report a case of duodenal and ileocecal tuberculosis successfully treated with diagnostic therapy using antituberculotic agent.