Non-anastomotic graft rupture in contemporary vascular prostheses is extremely rare and difficult to diagnose. We report a case of non-anastomotic vascular graft rupture diagnosed using non-obstructive aortic angioscopy. An 85-year-old male who underwent total arch replacement five years prior presented to our institution with chest pain. Based on contrast-enhanced angio-computed tomography and aortic angiography, we suspected extravasation of the thoracic vascular graft. Assessment of the vascular graft of the ascending aorta using aortic angioscopy revealed a red vascular graft defect. Non-anastomotic graft rupture was diagnosed by aortic angioscopy. The patient underwent 2-debranching thoracic endovascular aortic repair (Zone 0) with right subclavian artery-left common carotid artery-left subclavian artery bypass. Completion angiography and postoperative computed tomography showed the disappearance of the extravasation. Aortic angioscopy can help reach a definitive diagnosis in patients with graft rupture.