In recent year, cochlear implant (CI), which allows the deaf to acquire hearing, is being increasingly adopted as a new medicine in Japan as well. Cochlear implant is indicated for sensorineural hearing loss due to cochlear disorder. Information by speech is converted to electric signals to stimulate the auditory nerve with electrode array in the cochlea. On an average, 70–80% of speech has been recognized by the deaf who lose hearing after the period of speech acquisition postoperatively, and favorable results have been obtained among children, who have been implanted in early age of life. The advances in cochlear implant include miniaturization of the implantable part and improvement in a speech processor to the wearable type behind his/her ear(s). The coding strategy of speech signals also diversifies. In addition, the lowering of age for indication was also conducted in 1998 in Japan: children more than 2 years of age were included as candidates for the implantation. In Japan as well, auditory brainstem implant (ABI) was initiated for the treatment of hearing loss due to surgery for bilateral acoustic neurinoma. In the future, indications of CI will increase considerably by improvement in the device and contribution of speech auditory therapist to the medical care of CI users.