An image processing device which performs a tracking control with respect to a moving object which is travelling forward, based on the controlled variable of the own vehicle includes, an image processing unit which specifies an area of a moving object from an input image, sets the specified area of the moving object as a reference image area after starting tracking control, and sets an area of the moving object after a predetermined time as a comparison image area; a comparison unit which compares the set reference image area and the comparison image area with each other, and calculates travelling information relating to the moving object; and a controlled variable calculation unit which calculates a controlled variable of the own vehicle from travelling information which is calculated in the comparison unit.