A 2-month-old male infant was transferred to our hospital for suspected cardiomyopathy because he had livedo reticularis and peripheral coldness. An electrocardiogram showed ischemic change and an echocardiogram showed a dilated, poorly functioning left ventricle. Therefore, we performed urgent cardiac catheterization. The coronary artery was not visualized by aortography, but the single coronary artery arising from the pulmonary artery was depicted by pulmonary angiography. Therefore, we performed emergent surgery. The whole coronary arteries traveled directly inferiorly from the left side of the pulmonary trunk. A patent ductus arteriosus (PDA) was closed at the operation. We established cardiopulmonary bypass using two arterial cannulae through both ascending aortas and pulmonary trunk to maintain coronary blood flow. Direct implantation is difficult because the coronary ostium is far from the ascending aorta. Therefore, we chose to perform the Takeuchi procedure using an intrapulmonary artery tunnel. The patient's postoperative course was good, and he was discharged on postoperative day 22. A case of an anomalous origin of a single coronary artery from the pulmonary artery without any other heart disease is extremely rare. Management of cardiopulmonary bypass and myocardial protection in this abnormality is discussed.