To combine high-speed driving performance and low-speed driving performance of a light amount adjustment member when the amount of light is adjusted in an imaging apparatus.

Shading blades 1 to 7 adjust the amount of light passing through the opening of a base member 10. A rotation member 8 is driven by a first motor 11 to drive the shading blades. A projection part 8k is formed on the rotation member 8 and inserted into a long hole part 10d formed in the base member 10. The rotation range of the rotation member is restricted by the long hole part. A stopper member 15 is driven by a second motor 13 to change the moving range of the projection part 8k. When the amount of light passing through the opening is adjusted, the first or the second motor is selectively driven and controlled.