Aneurysm of the coronary artery associated with aortitis syndrome is extremely rare. This is a case report of a left coronary artery aneurysm associated with aortitis syndrome. The patient was a 47-year-old woman who complained of palpitation and dizziness on exertion. Aortogram revealed occlusion of the arch vessels, infrarenal aortic stenosis, and a fusiform aneurysm of the left coronary artery. There was neither an intraluminal thrombus nor occlusive changes in the coronary arteries. Severe systolic hypertension nearing 300 mmHg was present in the ascending aorta. Severe hypertension and direct extension of inflammation to the coronary artery seemed to be important factors for the formation of the aneurysm. To resolve the severe hypertension, a bypass operation between the ascending aorta and the abdominal aorta distal to the stenosis was performed. The postoperative course was uneventful and blood pressure was reduced.