Among chest trauma patients, cardiac laceration is a rare, but severe, condition requiring prompt management. Depending on the patient's hemodynamic status, early detection rate of a cardiac laceration may or may not be occur. If a possibility of cardiac laceration exists, an emergent thoracotomy should be performed. Furthermore, patients who experience a cardiac laceration also experience different kinds of complications. Therefore, close follow-up and monitoring are required. Herein, we report a 41-year-old man with a left atrium and a left ventricle laceration caused by a thoracic stab injury.