Hepatic hydrothorax refers to significant serous pleural effusion induced by liver cirrhosis, and some reports have suggested that this entity is ascites transferred to the thoracic cavity via a small hole in the diaphragm. There have been a few reports describing radical diaphragmatic repair by suturing the defect. We performed thoracoscopic diaphragmatic repair under abdominal insufflation to clarify the defect points. Air leakage at the diaphragmatic tissue was clearly noted and closed by suturing with polytetrafluoroethylene (PTFE) pledgets. The patient's postoperative course was uneventful, and no recurrence of ascites or hydrothorax has been noted.