A 74-year-old woman was admitted for the management of nausea with hyponatremia. On the 19th day of hospitalization, the patient developed cardiac arrest and needed cardiopulmonary resuscitation (CPR). CPR was successful but the patient developed multiple rib fractures with flail chest by CPR. Because of persistent dyspnea, surgery for fixing of the fractured ribs was performed using 4 titanium plates, with prompt improvement of the flail chest after the operation.