We present a case of an emergency operation on acute MR and cardiac rupture due to a blunt thoracic trauma. This 27-year-old male suffered a severe blow to the chest when his motorcycle crashed to a tree. He was brought to this hospital by ambulance. On admission, the patient was in shock due to hypotension. Echocardiogram revealed cardiac tamponade and MR of grade 3/4. Pericardial drainage was performed immediately and his condition improved. Systolic pressure of the pulmonary artery was high at 70 mmHg which measured by Swan Ganz catheter. Isolated cardiac injury was diagnosed based on the results of various tests. A sign of acute pulmonary edema progressively deteriolated, therefore, emergent operation was performed on the same day. As cardiac fissure lesions were confirmed under cardiopulmonary bypass, we repaired the inferior side of the left ventricle and then closely examined the mitral valve. Both anterior and posterior papillary muscles were completely torn, so we immediately commenced with procedures to, replace a prosthetic valve. No complication were encountered, and the postoperative course was good. Complete ruptures of the papillary muscles due to trauma is rarely reported. We believe this case is exceptionally uncommon and worthy of reporting.