Thoracic aortic dissection is a dangerous disease. It usually presents as severe chest or back pain. Symptoms resulting from aortic branch involvement may also be involved. Sometimes, it presents with atypical symptoms. Here, we report a patient who came to the emergency department (ED) because of acute onset of right upper limb weakness and numbness. Brain computed tomography (CT) was performed initially because cerebral vascular disease was suspected. Subsequently, angiography was performed as artery occlusion of the limb was found. The patient suddenly collapsed in the ED. Stanford type A acute aortic dissection was found by chest CT.