An image processing device includes: a delimiting line detection unit that detects a delimiting line candidate based on image data obtained by capturing a surrounding of a vehicle; and an exclusion determination unit that determines whether to exclude the delimiting line candidate. When a white delimiting line candidate having higher luminance than the road surface luminance and a black delimiting line candidate having lower luminance are detected, and one of the white and black delimiting line candidates is set as at least one first delimiting line candidate, and the other thereof is set as a second delimiting line candidate while the at least one first delimiting line candidate includes a pair of first delimiting line candidates between which the second delimiting line candidate is arranged and a distance between the pair is equal to or smaller than a threshold, the second delimiting line candidate is excluded.