We report that an earlier thoracoscopic clipping of the thoracic duct was advantageous in a case of post-operation chylothorax that occurred following thoracic aneurysm surgery. A 61-year-old man developed chylothrax on postoperative day 2 following graft replacement of the descending thoracic aorta using a left-sided thoracotomy. Since a replaced graft infection is lethal, earlier thoracoscopic clipping of the thoracic duct through the right side chest wall was indicated. The patient underwent thoracoscopic clipping on postoperative day 7 and was successfully treated. The duration of drainage was 2 days and oral intake was started on the seventh day. From our results, we recommend a thoracoscopic procedure through the opposite (right) side chest wall in the early stage of chylothorax development following thoracic aneurysm surgery.