Sudden deafness is a less-known symptom in patients with anterior inferior cerebellar artery (AICA) infarction, and its underlying mechanism is still unclear. In this report, the authors describe a case of a 63-year-old male who suddenly developed right deafness and vertigo. MR imaging on admission revealed cerebral infarction in the right AICA territory infarction. Precise neuro-otological examinations, including auditory brainstem response (ABR) and oto-acoustic emissions (OAE), Caloric test, first demonstrated that his deafness resulted from cochlear dysfunction. The authors emphasize that hearing impairment can be one of the neurological sequelae due to AICA infarction, and that precise neuro-otological examination may be important to clarify its underlying mechanisms.