PURPOSE: To improve an output sound pressure level without increasing the weight of the entire unit and its manufacturing cost by having a torque applied from a magnetic flux not only in the vicinity of the outer circumferential part of a magnet but also in the vicinity of the inner circumferential part so as to effectively utilize energy of the magnet.

CONSTITUTION: The speaker unit 11 is provided with a 1st cylindrical coil bobbin 3 fitted to the outer circumference of a torus magnet magnetized radially and a 2nd coil bobbin 4 fitted to the inner circumferential part and 1st and 2nd voice coils 1, 2 are wound respectively on the side face of the 1st and 2nd coil bobbins 3, 4. The 2nd coil bobbin 4 is connected to the 1st coil bobbin 3 by a sub diaphragm 14 and the 1st coil bobbin 3 is connected to the main diaphragm 16.