A speaker device comprising: a diaphragm ; and a frame for supporting the diaphragm , wherein a cross-section passing the center of the diaphragm and parallel to a sound emission direction includes sequentially from an inner periphery to an outer periphery of the diaphragm along the sound emission direction: a first bent plate portion ; a second bent plate portion having a cross-section in a convex arc shape; a third bent plate portion having a cross-section in a concave arc shape; and a fourth bent plate portion having a cross-section in a convex arc shape, and wherein an area of the first bent plate portion is larger than any of areas of the second, the third, the fourth bent plate portions (12-14), characterized in that the diaphragm is formed of a film containing polyimide; and the first bent plate portion has a cross-section in a concave arc shape; wherein curvature radius (R11) of the arc of the first bent plate portion is larger than curvature radius (R13) of the arc of the third bent plate portion , and curvature radius (R12) of the arc of the second bent plate portion is smaller than curvature radius (R13) of the arc of the third bent plate portion . a diaphragm ; and a frame for supporting the diaphragm , wherein a cross-section passing the center of the diaphragm and parallel to a sound emission direction includes sequentially from an inner periphery to an outer periphery of the diaphragm along the sound emission direction: a first bent plate portion ; a second bent plate portion having a cross-section in a convex arc shape; a third bent plate portion having a cross-section in a concave arc shape; and a fourth bent plate portion having a cross-section in a convex arc shape, and wherein an area of the first bent plate portion is larger than any of areas of the second, the third, the fourth bent plate portions (12-14), characterized in that the diaphragm is formed of a film containing polyimide; and the first bent plate portion has a cross-section in a concave arc shape; wherein curvature radius (R11) of the arc of the first bent plate portion is larger than curvature radius (R13) of the arc of the third bent plate portion , and curvature radius (R12) of the arc of the second bent plate portion is smaller than curvature radius (R13) of the arc of the third bent plate portion . a first bent plate portion ; a second bent plate portion having a cross-section in a convex arc shape; a third bent plate portion having a cross-section in a concave arc shape; and a fourth bent plate portion having a cross-section in a convex arc shape, and wherein an area of the first bent plate portion is larger than any of areas of the second, the third, the fourth bent plate portions (12-14), characterized in that the diaphragm is formed of a film containing polyimide; and the first bent plate portion has a cross-section in a concave arc shape; wherein curvature radius (R11) of the arc of the first bent plate portion is larger than curvature radius (R13) of the arc of the third bent plate portion , and curvature radius (R12) of the arc of the second bent plate portion is smaller than curvature radius (R13) of the arc of the third bent plate portion . <EOS>