To provide a diaphragm device, a light condensing device, an imaging device, and a program such that a result of composing a plurality of images with different exposure conditions can be generated by one time of exposure.

A diaphragm device that allows passage of a part of incident light includes: imaging means which receives an image transmitted through the diaphragm device having a mask that is obtained by combining a plurality of different masks h1, h2, and so on, on which a plurality of regions with transmission factors different from one another are formed, and that has at least three regions with transmission factors different from one another and which picks up the image; extraction means that extracts images transmitted through the masks h1, h2, and so on with respect to the picked up image; and composing means that generates a composite image of the extracted images.