In this study, a new subcutaneously implanted bone-conduction hearing aid is proposed. A vibrator unit of the hearing aid consists of two coils and an element made of giant magnetostrictive material (GMM). For the first stage in the development of the new boneconduction hearing aid, fundamental properties of the GMM vibrator were examined. In addition, a prototype transducer was made and installed in cadaver heads, and the performance of the prototype transducer was investigated. The output of the prototype transducer was linearly increased with increasing the input current. The frequency response varied depends on the cadavers. These results suggest that the gain of our hearing aid can be controlled by changing the input current, but individual differences of patients should be considered.