In this paper, we propose a method of measuring the reliability of direction-of-arrival (DOA) estimation results. One idea for the reliability measure arises from a waterbed effect in DOA estimation. The reliability measure can be obtained from the difference between the maximum and minimum point of cross-correlation. If the calculated reliability measure has a lower value than a predefined threshold, the estimated DOA is regarded as a wrong result and subsequently discarded. Some experiments show that the proposed method can reject perturbed results of the estimated DOA.