To provide a condenser microphone used for a reference of precise measurement of sound where leakage of hydrogen gas or helium gas from pin holes of vibrating membrane used for highly precise calibration and penetration of gas at a part with an uneven film thickness attended with rolling and extension unevenness can be prevented.

This invention is characterized in that a film is formed on a vibrating membrane to clog pin holes and to reinforce uneven thickness of the vibrating membrane due to uneven rolling and extension and a metallic film preventing gas leakage and penetration is used for the vibrating membrane of the microphone. A silicon fusion film or a fluorine fusion film such as glass fusion film is adopted for the film. In the microphone of this invention, an insulator, or an insulator to which especially silicon fusion film processing (especially glass fusion film processing) or fluorine fusion film processing is applied is especially preferred.