A case of ruptured callosomarginal artery aneurysm was reported. A 47-year-old male was admitted to our hospital with disturbance of consciousness. CT scan revealed subarachnoid hemorrhage. No aneurysm was detected by initial angiography. His consciousness level deteriorated so we stopped the examination. CT scan after initial angiography showed intracerebral hematoma in the left frontal lobe. On day 15 severe vasospasm occurred and he presented with total aphasia and right hemiplegia. The third angiography disclosed a callosomarginal artery aneurysm. Neck clipping of the aneurysm was successfully performed via unilateral interhemispheric approach. Postoperative course was uneventful and the patient recovered well with mild right hemiparesis and motor aphasia. He was transferred to another hospital for rehabilitation. The incidence of distal anterior cerebral artery aneurysm has been reported as being about 5%. The location of aneurysm in this case is very rare. In the present study we review the literature on aneurysms at the distal anterior cerebral artery and discuss the clinical and radiological features.