A 67-year-old man with dilated cardiomyopathy was admitted to our hospital for treatment of cardiac failure. After using heparin because cerebral infarction developed during hospitalization, in acknowledgment of thrombocytopenia, we reach the diagnosis of HIT. We judged surgery to be necessary because heart failure had difficulty with catecholamine secession and the left ventricular dilation progressed rapidly, and performed left ventriculoplasty, mitral valve plasty. There were no complications such as the thrombosis during cardiopulmonary bypass, and the postoperative course was good without leading to re-thoracotomy due to bleeding. He passes without a heart failure symptom by the follow of one year 6 months after surgery at home.