A loudspeaker device 1 includes an acoustic diaphragm 5 composed of a domed diaphragm 11, an edge-like diaphragm 13, and a junctional flat portion 12 which joins those domed and edge-like diaphragms, and a joined portion 23 where an end surface of a bobbin 4 of a voice coil or of a conductive 1-turn ring 3 is stuck and fixed to the junctional flat portion 12 or a reinforcement ring 15; and the reinforcement ring 15 is stuck and fixed to the junctional flat portion 12 from above or from under, thereby increasing the mechanical strength of the junctional flat portion 12 of the acoustic diaphragm 5. A loudspeaker device in which unnecessary vibrations are removed and also the quality of acoustic signals is excellent up to high range is provided.