An image processing unit 4 performs the recognition of a traffic signal in front of an own vehicle on the carriageway thereof. When the image processing unit 4 recognizes that there is a traffic signal front closet to the vehicle on the carriageway within a set distance L2 and the traffic signal is displaying red light, the process shifts to a stop line recognition mode and the image processing unit 4 performs stop line recognition. Accordingly, unnecessary execution of stop line recognition can be accurately avoided. Therefore, a stop line that is necessary for the control of the own vehicle can be recognized with a high accuracy without generating excessive calculation load.