An image processing device includes: a delimiting line detection unit configured to detect a delimiting line candidate based on image data obtained by capturing a surrounding of a vehicle; an exclusion determination unit configured to determine whether there is a parking-unavailable area in which parking of the vehicle is not permitted; and a parking space detection unit configured to detect the parking space based on the delimiting line candidate. In a case where plural parallel lines that are adjacent to the delimiting line candidate and that have a predetermined angle to the delimiting line candidate is detected, the exclusion determination unit regards an area in which the plural parallel lines are provided as the parking-unavailable area, and prohibits the parking space detection unit from detecting the parking space across the delimiting line candidate adjacent to the parking-unavailable area.