PURPOSE: A bone conduction speaker is provided to improve the contact with a curved skin surface by making the contact side of a mastoid with the skin surface gentle. CONSTITUTION: A driving unit changes electrical acoustic signal to a vibration signal. A vibration plate(30) amplifies the changed vibration signal. A mastoid(50) is projected from the outside of a housing and is contacted with a skull to transmit the amplified data. The vibration transfer member(40) is supported inside the vibration plate. A spherical hinge groove is formed at the center of the outside of the vibration transfer member.
