An impingement cooling structure comprising: a flow channel formed between a first wall and a second wall facing the first wall; a plurality of impingement cooling holes for injecting impingement jets of a cooling fluid into the channel along injection axes, the impingement cooling holes being disposed in the first wall such that the plurality of impingement cooling holes are spaced apart from each other along the flow channel in a transverse direction; and a flow diverter convexly protruding from a surface of the second wall in each space between injection axes of the plurality of impingement cooling holes, wherein the first wall includes a plurality of indentations concavely recessed along the flow channel toward a space between the flow diverters, and the plurality of impingement cooling holes are disposed in the indentation, so that the first and second walls (310, 320) define a wavy flow channel in which the indentations of the first wall and the flow diverters protruding from the second wall are alternately arranged; wherein the impingement jets after colliding with the second wall form wall jets that form a cross-flow in the transverse direction; wherein a cross-sectional shape of the flow diverter with respect to a plane including the injection axes is a triangular cross-sectional shape in which both sides form ridges that are each configured to raise the cross-flow of the wall jets to form a reflux, and wherein the flow diverter includes a bypass channel passing through the ridges of both sides along the flow channel for passing a portion of the wall jet in the transverse direction in the form of a small cross-flow. a flow channel formed between a first wall and a second wall facing the first wall; a plurality of impingement cooling holes for injecting impingement jets of a cooling fluid into the channel along injection axes, the impingement cooling holes being disposed in the first wall such that the plurality of impingement cooling holes are spaced apart from each other along the flow channel in a transverse direction; and a flow diverter convexly protruding from a surface of the second wall in each space between injection axes of the plurality of impingement cooling holes, wherein the first wall includes a plurality of indentations concavely recessed along the flow channel toward a space between the flow diverters, and the plurality of impingement cooling holes are disposed in the indentation, so that the first and second walls (310, 320) define a wavy flow channel in which the indentations of the first wall and the flow diverters protruding from the second wall are alternately arranged; wherein the impingement jets after colliding with the second wall form wall jets that form a cross-flow in the transverse direction; wherein a cross-sectional shape of the flow diverter with respect to a plane including the injection axes is a triangular cross-sectional shape in which both sides form ridges that are each configured to raise the cross-flow of the wall jets to form a reflux, and wherein the flow diverter includes a bypass channel passing through the ridges of both sides along the flow channel for passing a portion of the wall jet in the transverse direction in the form of a small cross-flow.