We report a case of aneurysmal rupture of the pancreaticoduodenal artery successfully treated by transcatheter arterial embolization. A 61-year-old man with a history of hypertension underwent surgery at our hospital in November 1995 for local peritonitis caused by perforation of the sigmoid colon secondary to cancer. On the 9th postoperative day, he developed shock, with complaints of epigastric and back pain. Abdominal computed tomography showed an enhanced mass, thought to be a peripancreatic aneurysm. Emergency angiography demonstrated an aneurysm arising from the arcade of the anterior pancreaticoduodenal artery. After diagnostic angiography, transcatheter arterial embolization was performed. With steel coils, the anterior superior pancreaticoduodenal artery and anterior inferior pancreaticoduodenal artery were embolized near the origin of the aneurysm. Angiography 7 weeks later revealed no recanalization of the aneurysm and the absence of anomalous collateral vessels. The patient has been well for 19 months without re-bleeding or recurrence of sigmoid colon cancer. Transcatheter arterial embolization is an effective therapeutic approach for aneurysm of the pancreaticoduodenal artery and is the preferred initial treatment.