We experienced a case of clipping of an intracranial aneurysm of a 63 year old male with a subarachnoid hemorrhage under general anesthesia. Preoperative electrocardiography showed complete Left Bundle Block (LBBB) without subjective symptoms. Among the intraventricular blocks, bundle branch block is the most common type and in particular, complete LBBB may progress to the more serious condition of complete heart block. Consideration of anesthetic management in such patients requires a knowledge of normal cardiac physiology, neurophysiology, the circulatory effects of various anesthetic agents and the pathophysiology of these diseases, to prevent any hypertension in response to intubation and surgery. We report upon the anesthetic management of a patient for clipping of an intracranial aneurysm with complete LBBB, which was performed successfully without complication.