PURPOSE: To expand the reproducing band and flat the sound pressure frequency characteristic, by supporting the rim part of the diaphragm composed only of a domed part with a frame through a soft elastic material and by impressing the driving force of the voice coil upon the area near the node at the 1st resonance time of the diaphragm.

CONSTITUTION: A magnetic circuit 12 is constituted by piling up a plate 14 having a center pole 13, a ring-shaped magnet 15, and a ring-shaped upper plate 16 in the described order. A frame 18 having a stepped section 17 is fixed to the upper surface of the magnetic circuit 12 and a soft material 19, such as a visco- elastic material, foamed resin, etc., is fitted to the stepped section 17. The rim part of a diaphragm 20 composed only of a domed part is placed on the soft elastic material 19 and the upper end of a voice coil 21 is coupled with the area corresponding to the node at the 1st resonance time of the diaphragm 20. Since the mechanical resistance of the vibrating section at the minimum resonance frequency is increased and the Q of the resonance is lowered when this constitution is realized, occurrence of the 1st resonance is prevented and the high band limit frequency is raised up to the 2nd resonance frequency.