To provide an inexpensive light quantity regulator which suppresses the occurrence of static electricity, and is excellent in operability.

The light quantity regulator incldues: a main plate A provided with an exposed opening; a light quantity regulation means freely movably supported by the main plate A and regulating the light quantity of the exposed opening; and an auxiliary plate B composed of a plate material made of the material same as that of the light quantity regulation means or a plate material having charging properties almost the same as those of that, interposed between the main plate A and the light quantity regulation means and forming the sliding part of the light quantity regulation means.

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