Cerebral infarction rarely occur following head injury. The authors present the case of a 39-year-old man with complete infarction in the middle cerebral artery[MCA] and anterior cerebral artery[ACA] territories ccurred immediately after head injury. He had compound depressed fracture in right frontal bone with no neurological deficit. After the depressed bone elevation, postoperative computed tomography scan showed the right MCA and ACA territory infarction with midline shift. Cerebral angiography obtained on the day after emergent decompressive craneictomy showed the complete occlusion of the internal carotid artery[ICA] at the level of lacerum ICA segment. There was no evidence of neck vessel dissection and basal skull fracture. Cerebral infarction can occur in an ultraearly period after head injury without neck vessel dissection or basal skull fracture. We stress the need for attention to the cerebral infarction as the cause of a rare neurological deterioration of the head trauma.