A 65-year-old man with chronic aortic dissection experienced two massive subcutaneous hemorrhages. Laboratory data indicated disseminated intravascular coagulation, whereas a contrast computed tomographic scan revealed a dilatated aortic arch with a partial thrombosis at the false lumen. Because disseminated intravascular coagulation can be caused by chronic aortic dissection, and the aortic arch was 6 cm in diameter, we performed graft replacement from the ascending to the descending aorta in a single stage. Before graft replacement, nafamostat mesilate, a protease inhibitor, was administered and the disseminated intravascular coagulation improved. Nafamostat mesilate may be useful for managing disseminated intravascular coagulation associated with chronic aortic dissection.