A housing structure of an acoustic controller, in which a lower case of the controller has an increased rigidity and improved moldability. The lower case is integrally formed by a resin and has a bottom surface thereof disposed to face a tabletop surface when the controller is in a stationarily placed thereon. The bottom surface of the lower case is formed to have a concave-forming portion that defines a concave space communicating with the outside of the controller on the left and right sides thereof and which is upward convex as viewed when the controller is stationarily placed, thus increasing the rigidity of the lower case. Bosses and vertical ribs formed to project upward from a horizontal part of the concave-forming portion of the lower case each have a reduced height, thereby improving the moldability of the lower case.