A horn for speakers includes a horn body including: a first opening located in a first end portion and having a circular shape; a second opening located in a second end portion and having a shape different from the circular shape; and a sound path connecting the first opening and the second opening. In a cross section including a central axis of the horn body, an inner surface of the sound path flares out in a quartic curve from the first opening toward the second opening. A length (L2) from the first end portion to the second end portion of the horn body is at least 0.8 times as large as a radius (R) of the first opening.