An azygos vein aneurysm is a very rare cause of a posterior mediastinal mass. Once the diagnosis has been confirmed, no treatment is usually required. However, the aneurysm can thrombose, and this may lead pulmonary thromboembolism, or the aneurysm may rupture. In these instances, the excision of the mass is recommended. Video-assisted thoracic surgery techniques have considerably improved. If it is necessary to remove the aneurysm, video-assisted thoracic surgery may be a good option for surgical treatment. We report a case of an aneurysm of the azygos arch that was successfully resected by video-assisted thoracic surgery.