Esophageal perforation due to blunt trauma is a rare clinical condition, and the diagnosis is often difficult because patients have few specific symptoms. Delayed diagnosis may result in a fatal clinical course due to mediastinitis and subsequent sepsis. In this article, we describe a 26-year-old man with esophageal perforation due to blunt chest trauma resulting from a motor vehicle accident. Because a severe disturbance of consciousness masked the patient's trauma-induced thoracic symptoms, we required 11 h to diagnose the esophageal perforation. Therefore, the patient developed septic shock due to mediastinitis. However, his subsequent clinical course was good because of prompt combined therapy involving surgical repair and medical treatment after the diagnosis.