An 82-year old man was admitted for a left fifth rib fracture with traumatic pneumothorax. Computed tomography showed a sharp rib fragment protruding into the thoracic cavity. Thoracic drainage was not performed before surgery to avoid lung injury by the rib fragment. At surgery, fifth rib fragment protruding into the thoracic cavity was found, but lung injury was not present. The bone fragment was removed, and the patient's postoperative course was uneventful.