Subdural hematoma (SDH) due to spontaneous rupture of intracranial aneurysm rarely occurs. The prevalence of subarachnoid hemorrhage (SAH) with SDH is approximately 0.5%-10.3% of all aneurysmal SAH. We report a case of aneurysmal rupture with SDH and SAH due to arachnoid defect after aneurysm clipping. The decedent was a 51-year-old woman who underwent brain surgery for SAH a few years ago. Two days before she died, she had nausea and sentinel headache. She was alive in the morning and was found dead at 6 PM. Injuries in the external surface were not found. A fresh SDH, measured approximately 90 mL, was found in the right hemisphere. SAH was diffusely distributed at the base of the brain and the right sylvian fissure. Two aneurysmal clippings were found in the anterior communicating artery and right internal carotid artery. A ruptured de novo aneurysm was also found in the right proximal middle cerebral artery. An uncal herniation was also observed. The cause of death was SAH with SDH due to de novo intracranial aneurysm. The tearing caused by the adhesion between the aneurysm and arachnoid, high blood pressure, and massive bleeding has been thought to be the causative mechanism of aneurysmal SAH with SDH. However, in this case, the arachnoid defect was caused by aneurysmal clipping through pterional approach. This defect served as the passage between the subarachnoid and subdural spaces. The autopsy for recurrent intracranial aneurysm will increase according to the extending life expectancy of patients after aneurysmal clipping.