To provide a light quantity adjusting device allowing implementation of the size reduction and high-speed shutter operation.

In the light quantity adjusting device which serves both as an exposure adjustment function and a shutter function and has a first driving ring 40 and a second driving ring 50, for driving a plurality of diaphragm blades 31, the first driving ring is driven by a first motor 80, and the second driving ring is driven by a second motor 86.