We report a 42-year-old female with alcohol addiction who suddenly died of subdural hematoma (SDH) caused by dural arteriovenous malformation (AVM). In autopsy, there was seen a massive SDH with a total weight of 181 g that covered an entire part of the left cerebral hemisphere, although either serious external injuries of the head or any visible internal injuries of the brain were observed. SDH subsequently resulted in the tonsillar, transtentorial and subfalcial herniations with a right-sided shift of the left-lateral and third ventricles, and the left thalamus as well. Histopathological examination on the serial sections cut from the falx cerebri revealed abnormal distribution of arteries and veins with various sizes, which were comprehensively highlighted by immunohistochemical stainings with alpha-SMA and CD31. Although a very point of bleeding was not identified even by careful histological observation, we concluded that dural AVM could be critical for acute SDH in the present case. The value of ethanol concentration examined in the samples from SDH supported that the lesion could be not chronic, but acute.