A sound source device of a horn according to one aspect of the present invention includes: a diaphragm; a movable iron core connected to the diaphragm through a support point; and a coil (bobbin and winding) into which a driving signal is inputted. The driving signal includes a first signal component that resonates with the diaphragm and a second signal component of a second frequency that resonates with the movable iron core of a first frequency and has a chord relationship with the first frequency. The support point is provided at a position eccentric from the center of the diaphragm, and the movable iron core is structured such that a gravity center is displaced further in an eccentric direction than the support point.