A 51-year-old Japanese male underwent on-pump coronary artery bypass grafting surgery. After weaning from cardiopulmonary bypass (348 min), sudden bradycardia and hypotension occurred, followed by ventricular fibrillation. Although defibrillation and infusion of catecholamine restored sinus rhythm, transesophageal echocardiography demonstrated severely reduced contraction of both ventricles, and perioperative vascular spasm was suspected. As vascular spasm was refractory to medications, percutaneous cardiopulmonary support (PCPS) system was quickly instituted under cardiac massage. Coronary angiography revealed vascular spasm of not only the native coronary arteries but also the implanted left internal thoracic artery. After 3 days of full hemodynamic assist, PCPS was withdrawn with no obvious abnormalities in regional wall motion by transesophageal echocardiography. The patient was extubated on postoperative day 6 with no impaired brain function. In this case, the immediate diagnosis of refractory vascular spasm by transesophageal echocardiography and full cardiocirculatory assistance by PCPS helped to save the life of the patient.