The authors report a 61-year-old female patient with a giant cavernous aneurysm in the right internal carotid artery (ICA) leading to acute subdural hematoma (ASDH) 7 days after the occurrence of abducens nerve palsy. She underwent ICA occlusion associated with high-flow bypass. In all five reported patients with a cavernous ICA aneurysm causing ASDH, the size of the aneurysm was giant and cranial nerve signs preceded the rupture. When a patient with a symptomatic cavernous ICA giant aneurysm experiences sudden-onset headache and/or consciousness disturbance, rupture of the aneurysm should be differentiated, even though a cavernous ICA aneurysm rarely causes ASDH.