We report a case of delayed massive hemothorax, a 72-year-old women, due to diaphragmatic injury by multiple lower rib fracture on 4th day aftrer traffic injury. We tried to stop bleeding by transcatheter arterial embolization, but the control of bleeding was difficult, necessitating the emergency surgery. The diaphragmatic injury about 3 cm diameter was found, and was sutured with absorption thread. The post operative course was uncomplicated. Patient was discharged on 51th day after injury. Careful observation is important for delayed hemothorax after lower rib fracture.