An in-vehicle device 4 includes an image acquisition unit 42 that acquires an image photographed by a camera 2 including a lens, a storage unit 7, a dirt detection unit 6 that detects dirt on the lens on the basis of the image acquired by the image acquisition unit 42 and that stores dirt region information indicating a region where the dirt exists in the image into the storage unit 7, a dirt removal information generation unit 8 that generates dirt removal information indicating a region where the dirt on the lens is removed, and a rewriting unit 12 that rewrites the dirt region information on the basis of the dirt removal information. Accordingly, it is possible to rewrite the dirt region information on the basis of the dirt removal information.