Background: Chronic pancreatitis with pseudocyst complicated by hemorrhage has a poor prognosis. Case Report: A 50-year-old Japanese male, known case of pancreatic pseudocyst presented with upper abdominal pain. Emergency CT demonstrated a hyper-attenuated area within the pancreatic pseudocyst, indicating a fresh hemorrhage. However, dynamic contrast-enhanced CT showed neither contrast extravasation nor pseudoaneurysm. Because laboratory data showed an increased serum level of pancreatic enzyme, diagnosis of acute exacerbation of chronic pancreatitis was considered. An arterial hemorrhage within the pancreatic pseudocyst was suspected, and angiography was performed to identify the bleeding site. The splenic angiography initially showed no definite findings of pseudoaneurysm or extravasation. CT during splenic arteriography revealed a splenic artery aneurysm and irregularity of the splenic artery branch at the proximal site of the pseudoaneurysm. Transcatheter arterial embolization was performed to prevent arterial bleeding from the pseudoaneurysm, and the injured segment of the splenic artery was embolized using 12 microcoils with an isolation method. Conclusion: Selective CT arteriography using interventional CT equipment might be useful in the three-dimensional evaluation of a minute or ambiguous visceral aneurysm on transvenous contrast-enhanced CT and selective angiograms.