An electro-acoustic transducer having a flat sound radiating plane is disclosed, in which a voice coil bobbin having a voice coil wound around an outer circumference thereof is inserted in an air gap defined by an inner pole piece and an outer pole piece and dome-shaped diaphragm is inserted in the voice coil bobbin to define a front chamber surrounded by curved surfaces of an outer surface of the diaphragm and an inner surface of the voice coil bobbin, and foamed synthetic resin is filled in the front chamber.