A 77-year-old man presented with transient motor weakness of the left hand. Cerebral angiography showed 90% stenosis at the origin of the right internal carotid artery. Carotid artery stenting (CAS) was performed 3 weeks later, and a large intraluminal thrombus was found during the procedure. The blood around the thrombus was aspirated using an aspiration catheter under distal protection with a filter wire protection device, and CAS was successfully performed without complications. Although this patient was treated by CAS without complications, carotid stenosis associated with intraluminal thrombus-because it has a high risk of distal embolism-should be carefully diagnosed immediately before CAS.