Pneumothorax occurs when the pleura ruptures and gas enters the pleural cavity. After the occurrence of pneumothorax, chest drainage by inserting a tube into the pleural cavity to remove the air is a common treatment. Generally, in most cases, after effective drainage for a few days, the lung can re-expand and the rupture can heal. Under these circumstances, it is common to clamp the drainage tube and observe for about two days. Then, a chest X-ray is re-examined and if there is no air, the tube can be removed. If air reappears after clamping, continued drainage is necessary. If the rupture does not heal and pneumothorax remains unresolved even after two weeks of drainage, and if the patient's physical condition allows, surgical treatment may be considered.