Surgical approaches to petrous cholesteatomas are the translabyrinthine–transcochlear approach, partial labyrinthectomy, and the middle cranial fossa approach. Selection of surgical approach is determined by region of cholesteatoma in the petrous bone as well as preoperative status of hearing and facial nerve function. The middle cranial fossa approach is the best approach for patient having good preoperative hearing and facial nerve function. However, application of this approach is limited for patients having relatively small petrous cholesteatomas, and sometimes difficult for patients in whom inner ear function is preserved but a cholesteatoma surrounds whole cochlea and extends to lower part of the labyrinth. In such case, we performed endoscope-assisted surgery via the middle cranial fossa approach to preserve cochlear and its function.30° and 70° rigid endoscopes were used for the operation via the middle cranial fossa.The inferior surface of the cochlea and the region around the internal carotid artery could be well visualized by use of endoscopy, and we succeeded in removal of petrous cholesteatoma surrounding the cochlea completely with preserving preoperative hearing.Endoscope-assisted surgical technique that allowed safe and complete removal of a cholesteatoma extended inferior surface of coclear and around carotid artery in the petrous.