A case of a ruptured dissecting aneurysm of the vertebral artery, which was detected by repeated angiography (third time), is reported. A 59-year-old woman, whose preoperative angiogram showed no abnormality, underwent a bifrontal craniotomy and the total removal of the right frontal glioma. However, a subarachnoid hemorrhage was detected by computed tomography the day after the surgery. Conventional angiography performed on the same day revealed no definite abnormality. Nevertheless, 9 days after surgery, a second subarachnoid hemorrhage occurred. The dissecting aneurysm of the vertebral artery was revealed by angiography. It is important to suspect this type of aneurysm as a differential diagnosis when the cause of the subarachnoid hemorrhage is not clarified in the first angiogram.