We describe the case of a 46-year-old woman in which a large intra-abdominal tumor was detected using computed tomography. It was a low-density, homogeneous, 7cm tumor, adjacent to the inferior vena cava (IVC). The tumor, along with a portion of the anterior wall of the IVC, was surgically resected. The tumor originated from the IVC wall, and histopathological examination revealed a diagnosis of leiomyosarcoma. The patient is alive without recurrence 10 years after surgery. Although this disease is rare and typically has a poor prognosis, complete resection with long-term survival is achievable.