A loudspeaker includes a diaphragm, an edge, and a voice coil. The diaphragm includes a groove having a concave cross section. Also, the diaphragm is in a horizontally or vertically elongated shape. The edge is coupled to an outer circumference of the diaphragm, and has a roughly half-round shaped cross section. The voice coil is bonded to the groove. The voice coil is thicker than a depth of the groove. Also, the voice coil has a cross section in which a dimension in a direction along a plane of the diaphragm is longer than a dimension in a direction perpendicular to the plane of the diaphragm.