We report a case showing delayed hemothorax superimposed on extrapleural hematoma after blunt chest injury. The patient was a 56-year-old man with a medical history of alcoholic hepatopathy who presented with a chief complaint of dyspnea on exertion. One month prior to presentation, he had sustained a fall that had resulted in left simple rib fracture. A chest radiograph taken at the time of injury showed notable reduction in the permeability of the left lung field along with high pulmonary collapse as well as rightward deviation of the shadow of the inferior mediastinum. Chest CT images showed a region of low absorption in the thoracic cavity with septi. Thoracic drainage was performed (1,300 mL total) and hemothorax was diagnosed. Thoracoscopic examination was then performed. When the inside of the thorax was observed, what had been presumed to be the septi of a multilocular fluid collection was found to be actually the parietal pleura, and a hematoma was confirmed inside the extrapleural cavity. The hematoma inside the extrapleural cavity was managed with lavage and drainage, and drainage tubes were placed inside both the thoracic cavity and extrapleural cavity at the end of the procedure. The patient's postoperative course was uneventful, and he was discharged on postoperative day 4.