A 59-year-old man, who suffered a massive pulmonary tumor embolism during surgery for renal cell carcinoma with vena caval invasion, was treated by emergency pulmonary embolectomy using cardiopulmonary bypass. Renal cell carcinoma occasionally extends into the inferior vena cava (IVC) as a tumor thrombus. In such patients, removal of the tumor thrombus from the IVC has to be performed in addition to radical nephrectomy. However, the massive pulmonary tumor embolism is a major potential hazard during radical surgical resection. To prevent intraoperative pulmonary embolisms from occurring, scheduled use of cardiopulmonary bypass with the cooperation of cardiovascular surgeons is recommended.