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 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 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. <EOS>