A severe but asymptomatic anemia developed in a patient with idiopathic thrombocytopenic purpura. Urgent upper gastrointestinal endoscopy disclosed massive bleeding from the papilla of Vater and we inferred that the anemia was caused by hemobilia. The bleeding point could not be detected, but the bleeding was stopped with conservative therapy. Although several cases of hemobilia have been reported in patients with bleeding tendency, this is the first case to be reported in a patient with idiopathic thrombocytopenic purpura.