Automatic wiper control prohibiting means prohibits execution of automatic wiper control when vehicle stop detecting means detects that a vehicle is stopping and a masking object detecting part determines that a masking object is adhered to an outer surface of a window part. When the vehicle stop detecting means detects that the vehicle is stopping and a state of the masking object detecting part is changed from a state where the masking object detecting part detects that the masking object is adhered to the outer surface of the window part to a state where the masking object detecting part detects that the masking object is not adhered to the outer surface of the window part at a changing time, the automatic wiper control prohibiting means prohibits the execution of said automatic wiper control for a predetermined period of time from the changing time.