Vascular injuries caused by cardiopulmonary resuscitation (CPR) can be associated with major complications. If patients who have received CPR have sudden abnormal hemodynamic findings, it is necessary to consider the possibility of these injuries. We report a 73-year-old man who had cardiac tamponade due to an injury to the internal mammary artery following manual chest compression. This very rare injury was detected by computed tomography and was treated by thoracotomy and hematoma evacuation.