Abstract: A horn speaker capable of forming a uniform sound field of a high fidelity and uniform tone quality and clearness, regardless of the position of listeners, suitable for use in broadcastings in a hall, station yard, playground and so forth. The horn speaker has a horn defined by four wall surface each of which is given by the equation of:a=a.sub.o (l+.alpha.x).sup.nwhere, a.sub.o represents the size of the throat, a represents the size of cross-section at a distance x from the throat and .alpha. represents the divergence coefficient. The n takes a value n.sub.1 (n.sub.1 .gtoreq.2) at the open end side of the horn and a different value n.sub.2 (n.sub.2 .gtoreq.n.sub.1) at the throat side. In addition, the tangential angle at the open end of the horn is selected to fall between 1.5.theta. and 2.0.theta., where .theta. represents a half of the directivity angle which is an angle causing a 6 dB drop of the sound pressure from the sound pressure on the axis of the polar directivity characteristics.