A dry etching method includes a first step of adsorbing first radicals into a surface of an etching target, wherein the first radicals are contained in first plasma generated from a plasma generator; and a second step of irradiating ion-beams extracted from second plasma generated from the plasma generator onto the surface of the etching target into which the radicals have been adsorbed, thereby desorbing a surface atomic layer of the etching target, wherein the first step is performed such that: a positive potential greater than a potential of the first plasma is applied to one or two selected from first to third grids, while a ground potential is applied to the rest thereof; and a negative potential equal to or lower than a potential of the third grid is applied to a substrate support structure.