I report a hemorrhagic complication due to disseminated intravascular coagulation after thoracic endovascular aortic repair for a dissecting aortic aneurysm. A 74-year-old man underwent thoracic endovascular aortic repair and carotid- carotid artery bypass to close the primary entry site of the dissecting aortic aneurysm. Postoperatively, he developed a gradually expanding cervical hematoma. Laboratory data showed disseminated intravascular coagulation. He could not extubated until postoperative day 6 because of the risk of airway obstruction. He was treated with transfusion to replenish the coagulation factor. Disseminated intravascular coagulation may occur secondary to thrombus formation in the false lumen after thoracic endovascular aortic repair.