An acoustic conversion device includes: a driving unit including a pair of magnets, a yoke, a coil, a vibrating portion which vibrates when driving current is supplied to the coil, and an armature disposed between the pair of magnets with the vibrating portion being passed through the coil; and a diaphragm unit including a holding frame having an opening, a resin film adhered to the holding frame, a diaphragm held within the holding frame, and a beam portion for propagating the vibration of the vibrating portion to the diaphragm; with the beam portion being combined with one edge side of the diaphragm, a predetermined gap being formed between the other edge of the diaphragm, and the inner face of the holding frame, a reinforcing member being provided to the predetermined gap, and the diaphragm being combined with the holding frame by the resin film and the reinforcing member.