We herein report on a patient with a cerebral aneurysm located at the petrous portion of the internal carotid artery (ICA). An 18-year-old male, previously diagnosed with neurofibromatosis, was referred to our emergency service complaining of severe headache, pulsatile tinnitus, nausea, and vomiting which occurred suddenly. Neuro-radiological studies including computed tomography and magnetic resonance imaging of the cerebral artery showed a large aneurysm arising from the petrous segment of the left ICA. He was treated with a neuro-interventional technique such as intra-arterial stenting and coil embolization for the aneurysm. Several days after the interventional treatment, his symptoms were resolved gradually except for a mild headache.Symptomatic unruptured aneurysm at the petrous portion of the ICA is rare, and our patient was treated successfully using a neuro-intervention technique. Therefore, we describe a case of a petrous aneurysm treated with endovascular coils without compromising the ICA flow, and review the literature.