Renal cell carcinoma generally invades renal veins and the inferior vena cava, and usually sends small pulmonary embolus. However, massive pulmonary embolism may rarely develop and it is fatal in most of the cases. We reported a 32-year-old man who suffered from massive pulmonary embolism during removal of renal cell carcinoma. Preoperative abdominal computerized tomography showed tumor involvement in renal vein and the inferior vena cava. Due to the intracaval extension below the diaphragm, he was scheduled for elective radical nephrectomy and thrombectomy of vena cava without cardiopulmonary bypass. During the dissection of venous thrombus, the patient developed a sudden cardiovascular collapse. Massive pulmonary embolism was suggested, although most of the hemodynamic and respiratory changes, excluding the increased central venous pressure and the decreased end-tidal carbon dioxide, could have been due to the massive bleeding. Although intraoperative pulmonary embolism was suspected, the diagnosis was not confirmed until the thoracic spiral computerized tomography scanning was performed during postoperative period. A large embolus occupying the lumen of right main pulmonary artery was identified in the contrast enhanced thoracic spiral computerized tomography. The patient underwent surgery for removal of the pulmonary emboli. During the operation, a large tumor thrombus was removed from the bifurcation of the pulmonary artery.