A coronary pseudoaneurysm is a rare complication of chest trauma. In this report, we describe the case of a 65-year-old man with a mediastinal lesion. On admission, he complained of chest tightness and dry cough, and a pseudoaneurysm was confirmed in the left anterior descending branch of the coronary artery on chest computerized tomography, angiography, and coronary angiography. The patient had experienced chest trauma 5 years previously. With the help of extracorporeal bypass surgery, the pseudoaneurysm was resected under direct observation. The patient recovered well after surgery. Traumatic coronary artery pseudoaneurysms usually are asymptomatic and often misdiagnosed. Preoperative coronary angiography is a crucial diagnostic used for deciding appropriate surgical management.