A rear warning system for a vehicle that detects information regarding an area behind a vehicle and is operated based on the detected information. The system includes sensors configured to detect the information regarding the area behind the vehicle and a guiding device operated by a controller to provide a notification of the information regarding the area behind the vehicle received from the sensors. The sensors include an ultrasonic wave sensor configured to detect a target object spaced farther from the rear of the vehicle than a predetermined distance and a capacitance sensor configured to detect the target object closer than or equal to the predetermined distance.