An omnidirectional camera system includes an omnidirectional camera that acquires an omnidirectional image by capturing using a fish-eye lens and an image processing device which displays the plurality of partial images which are cut out from the omnidirectional image side by side on one screen, in which the omnidirectional camera performs luminance adjustment with respect to the omnidirectional image, and the image processing device performs gradation adjustment processing in each partial image with respect to the plurality of partial images.