Anomalous origin of the right coronary artery is an extremely rare anomaly. We describe the case of a patient whose right coronary artery was arising from the ascending aorta with high takeoff. We diagnosed the anomaly incidentally during the operation. After transverse aortotomy for aortic valve replacement, we recognized the transection of the right coronary artery. The right coronary artery ostium was located approximately 5 cm above the right sinus of Valsalva. It was showing a complete transmural course. We repaired the right coronary artery by bypassing it with a saphenous vein graft.