PURPOSE: To obtain a satisfactory output without being aware of a speaker and with no difficulty to secure a necessary area by having a transparent speaker to the light by using a material transmissive to the visible light to constitute a diaphragm and a fixed electrode.

CONSTITUTION: A transparent conductive film 2 is adhered to a fixed electrode supporter 1 made of an acrylic resin plate. These supporter 1 and the film 2 form a fixed electrode 10. An insulated spacer 3 is made of acrylic resin, etc., and a transparent conductive diaphragm 5 is bonded to a diaphragm feame 4. An acrylic resin pressure plate 6 is fixed with a plastic screw 7 to the spacer 3 by sandwiching the diaphragm 5 and the frame 4. Thus the diaphragm 5 is spread at a prescribed position. The gold is vapor-deposited to a 6μm polyethylene terephthalate film to obtain a material for the diaphragm 5. This diaphragm 5 has 6Ω/square sheet resistance and about 30% transmissivity of visible light.