1. An image processing device that processes a pair of images imaged by a pair of imaging elements at the same time in the same direction, the device comprising: one image object region extraction means configured to recognize an object, parallax information of which is to be acquired from one image, and to extract one image object region that is an imaged region including an image of the object in the one image; the degree of background calculation means configured to calculate the degree of background that is likelihood of whether either an object image configuration part that configures an image of the object, or a background image configuration part that configures an image of a background other than the object with respect to a plurality of image configuration parts that configures the one image object region; and a parallax calculation means configured to extract the other image object region having an image similar to the one image object region from the other image, and to calculate a parallax between the one image object region and the other image object region.