Two cases of diaphragmatic hernia by blunt trauma were experienced. One patient was a 21-year-old man who had been injured in a car collision 4 days before was transferred to our division from another hospital. Another patient was a 66-year-old man who was admitted in an emergency after a fall from a height. Both patients were suspected from chest X-ray and computed tomography (CT) to have traumatic rupture of left diaphragm, and were successfully performed repair of the diaphragm by thoracic approach. Since the diagnosis of ruptured diaphragm is frequently missed in the acute phase, a careful scrutiny of the chest X-ray is required. Laparotomy is the operative approach of choice in the case with the associated abdominal injuries. On the other hand, thoracotomy is selected for the patients accompanied with the lung injury or in the latent phase. Although diaphragmatic rupture can be managed by the appropriate treatment, the associated injuries or complications are responsible for the high mortality.