A moving obstacle deciding apparatus includes a search signal transmitting and receiving section 1 for transmitting a search signal, and for receiving the search signal reflected from a search target as a detection signal; a decision reference value calculating section 6 for calculating a decision reference value based on the detection signal received by the search signal transmitting and receiving section 1; and a moving obstacle deciding section 10 for making a decision as to whether the search target is a moving obstacle or not in accordance with a compared result of a difference value between decision reference values obtained by the decision reference value calculating section 6 in time-series searches with a prescribed threshold.