Transposition of the great artery is one of common congenital cardiac disease resulting cyanosis. Death occurs easily in untreated patients with transposition and intact ventricular septal defect (VSD) in infancy at a few days of age when posterior descending coronary artery (PDA) closed. Since there are 2 parallel circulations, flow from pulmonary to systemic circulation is necessary for systemic oxygenation, and Balloon atrial septostomy or prostaglandin infusion should be performed especially if patient do not have VSD. Although the advent of fetal echocardiography, it is difficult to diagnose the transposition of the great arteries (TGA) as abnormality of great vessels is relatively undistinguishable. The diagnosis of transposition is in itself an indication for surgery, and arterial switch procedure is performed in the case the left ventricle pressure remains more than 2/3 of systemic pressure. Preoperative diagnosis is important as associated anomalies and coronary artery branching patterns are important to decide the operative indication and timing of surgery.