Severe acute pancreatitis is not uncommon clinically, but is not so often if complicated with psudoaneurysm formation. Once the pseudoaneurysm rupture, it always induces hypovolemic shock and high mortality rate. The patient is a 36 year-old man, who was admitted due to alcohol related acute necrotizing pancreatitis. Massive upper gastrointestinal bleeding with hypovolemic shock developed on 10th day, angiography revealed a ruptured gastroduodenal artery pseudoaneurysm. Angioembolization was effective for hemostasis.