A 67-year-old male was referred to our hospital after being diagnosed with esophageal squamous cell carcinoma of the middle thoracic esophagus. The clinical stage was T1b(sm)N4M1 cStage IVb, so he was admitted to our hospital for systemic chemotherapy. He had sustained fever and a dry cough. Chest computed tomography showed the presence of irregular shadows, and unidentified respiratory insufficiency had progressed. A transbronchial lung biopsy revealed a pulmonary artery tumor embolus of esophageal squamous cell carcinoma. He developed DIC and died of respiratory failure on the 19th hospital day. The postmortem autopsy detected pulmonary tumor thrombotic microangiopathy accompanied by esophageal squamous cell carcinoma.