The image processing device includes a lane marking recognition section that recognizes left and right lane markings from a surroundings image captured by an imaging section, and a leading vehicle recognition section that recognizes a leading vehicle from the surroundings image. The lane marking recognition section determines that the left and right lane markings are a true lane marking pair in cases in which a width direction discrepancy, or a value based on the discrepancy, between a reference position between the left and right lane markings and a reference position of the leading vehicle is within a threshold value.