A driver assist system configured to accurately recognize a target vehicle in a communication area set in front of a vehicle to assist a driver to operate the vehicle. The driver assist system notifies a driver of existence of the target vehicle in the communication area. A controller comprises: a timer that measures an elapsed time from a point at which the target vehicle moved out of the communication area; and a recognizer that recognizes other vehicle as a target vehicle until the elapsed time exceeds a threshold period of time, and that cancels a recognition of other vehicle as the target vehicle when the elapsed time exceeds the threshold period of time.