A transmission and reception device is located at a predetermined height on a movable object and directed toward an outside. The transmission and reception device includes a transmission unit for repeatedly transmitting sensing waves at a predetermined interval and a reception unit for receiving reflective waves of the sensing waves from a detected object. A peak value detecting unit detects peak values of the received reflective waves and stores the detected peak values. A difference arithmetic unit calculates a difference in the detected peak values with movement of the movable object closer to the detected object. An object determination unit determines the detected object to be a near-road-surface obstacle, which is close to a road surface, when the difference is a negative value. The object determination unit determines the detected object to be an other obstacle than the near-road-surface obstacle when the difference is a positive value.