Abstract: An obstacle sensing apparatus uses an FM-CW wave as an emitted wave to an object in front of a car. A received wave from the object is mixed with the emitted wave to produce a beat signal which is analyzed in frequency to measure a distance and a relative speed with respect to the object. A distance and a relative speed at the next time is predicted from the measured distance and relative speed. The object is determined to be a car if the relative speed does not have an approaching direction or substantially the same value as a sensed car speed. The object is otherwise determined to be at least one of a guardrail and a sound barrier if a difference between the measured distance and the predicted distance exceeds a preset value and a plurality of the last measured distances are substantially constant. The object is otherwise determined to be a stationary object other than the guardrail.