A case changing blood pressure severely by manipulation of the huge tumor mass during the brain tumor surgery was observed. Decreased blood pressure (55/35 mmHg) might be caused by the stimulation of the brain increased to 150/75 mmHg after a neurosurgeon undermined and elevated the tomor mass, and blood pressure decreased again to 55/35 mmHg when he put it on the same position. Removing the mass completely, blood pressure was stabilized (about 130/70 mmHg). There are central vasomotor centers of autonomic nervous organization in the hypothalamus, midbrain, pons or medulla oblongata of the brain. By the stimulation of specific region in the above area, various features of responses were anatomically defined. The supratentorial contents may herniate through the tentorial incisura into the infratentorial spaces and posterior fossa, when intracranial pressure gradients become large enough to overcome the resistance of the brain tissue, and they can affect vital changes.