The present disclosure relates to provide an active erroneous sample elimination device or erroneous sample elimination method for a relay capable of correctly implementing erroneous sample elimination processing even during a plurality of electrical disturbances mixed with an electrical quantity detection signal, and a digital protective relay according to the present disclosure may include a converter that samples an analog signal and converts the sampled signal to a digital signal; and a processor that searches an inflection point at which an electrical variation quantity varies from an increase to a decrease or from a decrease to an increase based on the digital signal, and compares an electrical variation quantity prior to and subsequent to the inflection point with a preset electrical quantity.