Superficial siderosis of the central nervous system (CNS) is a progressive disease of the CNS associated with persistent or chronic subarachnoid hemorrhage. The classic symptoms are bilateral sensorineural hearing loss, cerebellar ataxia and myelopathy. Sensorineural hearing loss is a particularly important symptom which occurs early in the disease and ultimately affects 95% of cases. The failure site associated with hearing loss due to the disease is retrocochlear, and peripheral or both of them coexist. However, the detailed mechanism is not known. We describe herein a 57-year-old woman with superficial siderosis who underwent cochlear implantation for bilateral profound hearing loss. The performance score on the word recognition test was 72%. However, the speech perception started to worsen at 18 months after the operation. Prolonged follow-up may be therefore required to evaluate the benefit of cochlear implantation for profound hearing loss associated with superficial siderosis.