A 16-year-old boy developed motor aphasia and right hemiplegia after head trauma caused during Rugby football club activity. About 2 hours after trauma, these neurological deficits improved dramatically. CT scan on admission revealed no abnormal finding. But, on the next day, CT scan revealed an irregular low density area at the left basal ganglia. Cerebral angiography showed a slight narrowing at the left carotid siphon, severe stenosis at M1 portion of the left middle cerebral artery with vasospasm of its distal branches and occlusion of the left anterior temporal artery. The extracranial portion of the left internal carotid artery was intact. Clinically, the patient recovered from the right hemiparesis almost fully and was discharged after 1 month with mild dyscalculia. Three months later, follow-up angiography disclosed stenosis of the left M1 portion but the narrowing of the carotid siphon and vasospasm of the peripheral branches of the middle cerebral artery had been normalized, and the anterior temporal artery was recanalized. The pathogenesis of the occlusion is classified into 4 causes, 1) embolism from internal carotid artery, 2) vasospasm, 3) thrombus formation, 4) dissection. However, the demonstration of this by angiography is difficult. In our case, the injury of the intracranial portion of the internal carotid artery, which caused the intimal injury, spasm or thrombus formation, might have happened and resulted in embolisation and recanalization of the middle cerebral artery.