A driving assistance system to provide various kinds of information to a driver of a moving object (V) from an image-capturing result of surroundings of the moving object (V), comprising: image-capturing means installed on the moving object (V) and configured to capture a surrounding image (I) including a portion (P) of the moving object (V); first edge line storing means configured to store a first edge line (E1) detected for the portion (P) of the moving object (V) from a first surrounding image (I) captured in advance by the image-capturing means in normal conditions when no raindrops are attached to a lens unit of the image capturing means ; edge detecting means configured to detect a second edge line (E2) for the portion (P) of the moving object (V) from a second surrounding image (I) currently captured by the image-capturing means ; calculating means configured to calculate a deviation degree between the first edge line (E1) stored in the first edge line storing means and the second edge line (E2) detected by the edge detecting unit; raindrop judging means configured to judge that a raindrop is attached to the lens unit of the image-capturing means , when the deviation degree between the first edge line (E1) and the second edge line (E2) is equal to or larger than a predetermined value, and detection sensitivity lowering means configured to lower sensitivity of detection of another moving object from the second surrounding image (I) currently captured by the image-capturing means by raising a detection threshold to detect another moving object from the second surrounding image (I), when the raindrop judging means judges that a raindrop is attached to the lens unit of the image-capturing means and the deviation degree between the first edge line (E1) and the second edge line (E2) is lower than a preset given value which is a value larger than the predetermined value. image-capturing means installed on the moving object (V) and configured to capture a surrounding image (I) including a portion (P) of the moving object (V); first edge line storing means configured to store a first edge line (E1) detected for the portion (P) of the moving object (V) from a first surrounding image (I) captured in advance by the image-capturing means in normal conditions when no raindrops are attached to a lens unit of the image capturing means ; edge detecting means configured to detect a second edge line (E2) for the portion (P) of the moving object (V) from a second surrounding image (I) currently captured by the image-capturing means ; calculating means configured to calculate a deviation degree between the first edge line (E1) stored in the first edge line storing means and the second edge line (E2) detected by the edge detecting unit; raindrop judging means configured to judge that a raindrop is attached to the lens unit of the image-capturing means , when the deviation degree between the first edge line (E1) and the second edge line (E2) is equal to or larger than a predetermined value, and detection sensitivity lowering means configured to lower sensitivity of detection of another moving object from the second surrounding image (I) currently captured by the image-capturing means by raising a detection threshold to detect another moving object from the second surrounding image (I), when the raindrop judging means judges that a raindrop is attached to the lens unit of the image-capturing means and the deviation degree between the first edge line (E1) and the second edge line (E2) is lower than a preset given value which is a value larger than the predetermined value. <EOS>