In acute Stanford type A aortic dissection, except for some thrombosed false-lumen types, graft replacement is a standard treatment. On the other hand, thoracic endovascular aortic repair (TEVAR) might be considered for high-risk patients with retrograde type A aortic dissection when entry is in the descending aorta, although its efficacy in a case of an extensive thrombosed false lumen without obvious entry is unknown. We report a case of successful zone 3 TEVAR using RelayPro NBS for Stanford type A aortic dissection with a localized CT-enhanced false lumen in the proximal descending aorta. An 83-year-old woman was admitted for acute Stanford type A aortic dissection with a thrombosed false lumen of the ascending thoracic aorta. She was initially treated conservatively because of being a high-risk patient for open surgery. One week after hospitalization, the ascending aorta diameter increased and the false lumen in the proximal descending aorta grew sporadically in a CT image. We suspected that the ascending aorta was enlarged due to a partially patent false lumen of the descending thoracic aorta, and performed zone 3 TEVAR using RelayPro NBS to close a possible entry in the proximal descending aorta even though there was no obvious entry. The patient had a good postoperative course and was discharged 15 days after TEVAR. Shrinkage of the false lumen in the ascending aorta was observed in CT images two months after TEVAR.