DRIVING ASSISTANCE DEVICE AND RAINDROP DETECTION METHOD THEREFOR

A driving assistance system 1 is installed in a moving object and includes; image-capturing means 10 to capture a surrounding image I including a portion of the moving object, first edge line storing means 22 to store a first edge line E1 detected from a first surrounding image I captured in normal conditions by the image-capturing means 10, and calculating means 23 to calculate a matching degree between the first edge line E1 and a second edge line E2 detected from a second surrounding image I currently captured by the image-capturing means 10. A raindrop judging means 24 judges that a raindrop is attached to the lens unit of the image-capturing means 10 in response to a decrease in the matching degree between the first edge line E1 and the second edge line E2.