To provide an exposure setting device capable of optimizing an exposure of a camera installed on a mobile body when moving.

A GPS in-vehicle device 22 acquires a change in a position of an in-vehicle camera 10 capable of exposure setting, and an inclination sensor 24 acquires a change in an optical axis direction. An image processing unit 30 sets one area or a plurality of image areas capable of varying positions for each image acquisition timing in an image acquired by the in-vehicle camera 10, acquires a luminance of each pixel constituting the image area, and calculates an evaluation value for respectively determining whether or not the plurality of image areas are incompatible areas estimated that image processing cannot be performed due to excess and deficiency of an exposure on the basis of the acquired luminance. Position coordinates of the plurality of set image areas are changed to position coordinates of predetermined areas on the basis of at least one of the change in the position of the in-vehicle camera 10 or the change in the optical axis direction of the in-vehicle camera 10 when it is determined that one of the plurality of image areas is incompatible.