Pseudoaneurysm occurs rarely after percutaneous cannulation of a peripheral artery. A 90 years old male patient with cholangiocarcinoma of distal common bile duct was underwent palliative surgery. Arterial cannulation of a dorsalis pedis artery was done for continuous arterial blood pressure monitoring and blood sampling, and it was removed 7 days after cannulation. Pseudoaneurysm was developed 25 days after cannulation. We report the pseudoaneurysm of dorsalis pedis artery and describe the related mechanisms and predisposing factors.