Pulmonary thromboembolism originated most commonly from the venous thrombus, especially deep vein thrombus in the leg, which migrated to and occluded the pulmonary vasculatures. The failure of clot lysis and repeated embolic episodes resulted in the hemodynamic compromise -that is- in the increasing in the pulmonary vascular resistance, which would cause the right ventricle failure[Car Pulmonale]. Under the cardiopulmonary bypass, 20 year old male patient was treated successfully by thromboembolectomy of pulmonary thromboembolism with pulmonary hypertension, which originated from the deep vein thrombus in the leg. The results of radiologic studies and clinical evaluations were excellent in that the postoperative lung perfusion scan showed the newly increased perfusion of post-embolectomy territories and in the arterial blood gas finding of 76 from 66[mmHg] in PaO2. The patient was uneventful and discharged on postop. $ 14 days with anticoagulant continued.