Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common genetic disorders and is characterized by the development and progressive enlargement of cysts in the kidneys. ADPKD is caused by mutations of either PKD1 or PKD2. The prevalence of brain aneurysm in patients with ADPKD is increased, and subarachnoid hemorrhage (SAH) from a ruptured intracranial aneurysm is one of the frequent complications. We describe an autopsy case of death of a 31-year-old woman by aneurysmal SAH. ADPKD as an underlining disease was suggested by the autopsy findings. Sequence analysis of the PKD1 and PKD2 genes revealed deletion of a guanine at position 8019 in PKD1 (8019delG) in a heterozygous state resulting in a shift in the reading frame and generation of a premature termination codon at amino acid 2684 (G2673fs12X). This mutation is novel and highly suspected as the causal mutation of ADPKD of this case.