PURPOSE: To eliminate a damage due to the cutting of a lead wire or a disconnection is soldering by moving a field magnet without moving a coil and pulling and oscillating the lead wire by the coil.

CONSTITUTION: The stator voice coil 23 is disposed in the cylindrical magnetic gap 30 of a magnetic circuit. The field magnet 22 made of a cylindrical and radially anisotropic magnet material having an internal and an external faces magnetized to different poles so as to be axially movable in the magnetic gap 30 through this stator coil 23 and the radial magnetic gap 30 is disposed. The end part of an oscillator 21 interlocking with the axial oscillating movement of this field magnet 22 is extended to enclose and protect the field magnet 22 in this extending part. The oscillator 21 is formed of a thin film plastic.