The case of a patient with a thoracoabdominal aortic aneurysm accompanied by a shaggy aorta, in whom embolism was prevented by a graft used in debranching and placement of an extracorporeal shunt during thoracic endovascular aortic repair, called the "block and trap method", is presented. Two-staged operations were performed using Y graft replacement, debranching bypass, and thoracic endovascular aortic repair during which a temporary shunt line with a blood filter was made involving the femoral artery and vein. The method of trapping emboli in a filter in an external shunt appears effective.