PURPOSE:To obtain a diaphragm which has the high modulus of elasticity and a good-linearity edge by adhering and laminating light metal foil and a polymer film form a diaphragm, and leaving the light metal foil at the edge of the diaphragm linearly only in a tangential direction by an etching treatment. CONSTITUTION:A dome-shaped diaphragm 21 for a headphone is formed of, for example, polyester 6mu, an adhesive (polyester) 2mu, aluminum foil 12mu by dry coating. The edge part 22 has the aluminum foil left almost linearly only in tangential directions by etching the lamination film and is formed simultaneously with the dome-shaped diaphragm 21 having a roll shaped section. A voice coil 3 is adhered to the boundary part between the diaphragm 21 and edge 22 to drive the diaphragm 21. The edge structure is used to improve the linearity, to reduce distortion originating from the edge and the occurrence of a rolling phenomenon.