We report a case of subarachnoid hemorrhage at the skull base with possible rupture of a vertebral artery, and we present a new method to investigate rupture of this artery. In this method, the brain stem and cerebrum are divided with ligation of the internal carotid artery and basilar artery, and milk is injected from the original part of the vessel to find the rupture. We show that this method is particularly useful for cases of subarachnoid hemorrhage at the skull base in which there may be rupture of a vertebral artery.