Adhered substance detection apparatus

An adhered substance detection apparatus that determines whether a substance is adhered to an image-capturing apparatus, the adhered substance detection apparatus comprising a controller configured to function as:

• an extractor that extracts candidate regions for being an adhered substance region in which the substance is adhered to the image-capturing apparatus, the candidate regions being extracted based on an edge that is detected from pixels in a captured image captured by the image-capturing apparatus;
• and
• a final determiner that finally determines whether the candidate regions are the adhered substance region, based on, among the candidate regions extracted by the extractor, i) an area of the candidate regions located in a first region of the captured image, the first region including a road surface region in the captured image and ii) an area of the candidate regions located in a second region of the captured image, the second region including a region other than the road surface region in the captured image.