A 12-year-old female presented with the abnormal findings on the chest PA. The chest CT revealed a retrosternal defect of the diaphragm and a fatty opacity in the pleural cavity, resulting in a diagnosis of Morgagni hernia. It was decided to undergo a laparoscopic surgery. The retrosternal defect of the diaphragm measuring 3.5 cm in diameter was found, through which a portion of the greater omentum and the fatty tissue connected with the falciform ligament were herniated into the pleural cavity. The greater omentum was pushed back into the peritoneal cavity and the fatty tissue connected with falciform ligament was excised. The mediastinal pleura was plicated and the defect of the diaphragm was repaired primarily. Immediately after the operation, the patient developed a right pneumothorax for which a chest tube was inserted. She was discharged at the post-operative third day without any further complications.