Although paraplegia following descending thoracic and thoracoabdominal aortic repair is well known, paraplegia after repairing ascending aorta has been rarely reported. We describe a very rare case of postoperative paraparesis after repairing type A acute aortic dissection. A 64-year-old man with type A acute aortic dissection whose aortic false lumen was all thrombosed, was treated with rest and his blood pressure was strictly controlled. The follow-up computed tomography revealed that blood flow in the false lumen was recognized in the ascending aorta 8 days after admission. At the same time the diameter of the ascending aorta was enlarged. We performed emergency ascending aortic replacement under deep-hypothermic circulatory arrest and selective cerebral perfusion. We recognized that he showed paraparesis 4 days after operation and magnetic resonance imaging showed high signals in the spinal cord, which indicated spinal cord infarction. He received rehabilitation for 5 months, and fully recovered neurologically. The causes of paraplegia after repairing type A acute aortic dissection have not been clarified. In our case, we presumed the causes included over 60 min circulatory arrest which invoked low spinal perfusion, the anterior spinal artery was thrombosed by selective cerebral perfusion, some intercostals arteries were occluded by postoperative change of the descending aortic false lumen pressure. This case is very rare, and we had to take all possible precautions.