We report a case of leiomyosarcoma of the inferior vena cava, which was successfully treated by surgical en bloc resection and reconstruction of the inferior vena cava, followed by adjuvant radiation therapy. A 39-year-old man presented with nausea, vomiting, epigastric pain, and weight loss. Radiologic examinations showed a mass originating from the inferior vena cava and surgical resection was performed. Histopathological examination of the specimen revealed a moderately differentiated (grade II) leiomyosarcoma arising from the inferior vena cava. We believe that radical resection with clear surgical margins followed by adjuvant radiation therapy is a good curative strategy for achieving any chance of long-term survival.