There is provided a static eliminator for accurately detecting a contamination condition of a discharge electrode, in which a target value as a target frame ground current value is changed from, for example, zero as a reference alternately to the plus side and the minus side to such a degree as not to affect the ion balance of a workpiece, and the follow-up time, namely a phase delay, with respect to the change in target value differs depending on the contamination condition of the discharge electrode, and becomes longer with the progress of the contamination, and by use of this characteristic, a plurality of thresholds are prepared and compared with a detected frame ground current value, so as to detect the contamination condition of the discharge electrode.