A gas turbine comprising: a housing; a rotor rotatably provided in the housing; a turbine blade configured to receive rotating force from combustion gas and rotate the rotor; a turbine vane configured to guide a flow of the combustion gas toward the turbine blade, the turbine vane having a turbine vane cooling passage for delivering cooling fluid to an inner wall of the turbine vane; and an impingement plate installed in the turbine vane cooling passage, the impingement plate having a plurality of injection holes (712, 714, 722, 724, 730) through which the cooling fluid is injected onto the inner wall of the turbine vane, the injection holes (712, 714, 722, 724, 730) formed at predetermined locations of the impingement plate, wherein the injection holes (712, 714, 722, 724, 730) are formed differently depending on locations of the injection holes (712, 714, 722, 724, 730), wherein the turbine vane comprises: a turbine vane platform part formed in an annular shape along a rotation direction of the rotor; and a turbine vane airfoil part extending from the turbine vane platform part in a rotational radial direction of the rotor; wherein the impingement plate is configured to inject cooling fluid onto an inner wall of the turbine vane airfoil part; and wherein the injection holes (712, 714, 722, 724, 730) comprise: a center-side injection hole disposed at a center side with respect to an extension direction of the turbine vane airfoil part; and an end-side injection hole disposed at an end side with respect to the extension direction of the turbine vane airfoil part, wherein a number of end-side injection holes per unit area is greater than a number of center-side injection holes per unit area, characterised in that a thickness of the wall of the turbine vane airfoil part is gradually increased from the center side to the end side, and the injection holes (712, 714, 722, 724, 730) are formed such that the number of injection holes (712, 714, 722, 724, 730) per unit area is gradually increased from the center side to the end side. a housing; a rotor rotatably provided in the housing; a turbine blade configured to receive rotating force from combustion gas and rotate the rotor; a turbine vane configured to guide a flow of the combustion gas toward the turbine blade, the turbine vane having a turbine vane cooling passage for delivering cooling fluid to an inner wall of the turbine vane; and an impingement plate installed in the turbine vane cooling passage, the impingement plate having a plurality of injection holes (712, 714, 722, 724, 730) through which the cooling fluid is injected onto the inner wall of the turbine vane, the injection holes (712, 714, 722, 724, 730) formed at predetermined locations of the impingement plate, wherein the injection holes (712, 714, 722, 724, 730) are formed differently depending on locations of the injection holes (712, 714, 722, 724, 730), wherein the turbine vane comprises: a turbine vane platform part formed in an annular shape along a rotation direction of the rotor; and a turbine vane airfoil part extending from the turbine vane platform part in a rotational radial direction of the rotor; a turbine vane platform part formed in an annular shape along a rotation direction of the rotor; and a turbine vane airfoil part extending from the turbine vane platform part in a rotational radial direction of the rotor; wherein the impingement plate is configured to inject cooling fluid onto an inner wall of the turbine vane airfoil part; and wherein the injection holes (712, 714, 722, 724, 730) comprise: a center-side injection hole disposed at a center side with respect to an extension direction of the turbine vane airfoil part; and an end-side injection hole disposed at an end side with respect to the extension direction of the turbine vane airfoil part, wherein a number of end-side injection holes per unit area is greater than a number of center-side injection holes per unit area, characterised in that a thickness of the wall of the turbine vane airfoil part is gradually increased from the center side to the end side, and the injection holes (712, 714, 722, 724, 730) are formed such that the number of injection holes (712, 714, 722, 724, 730) per unit area is gradually increased from the center side to the end side. a center-side injection hole disposed at a center side with respect to an extension direction of the turbine vane airfoil part; and an end-side injection hole disposed at an end side with respect to the extension direction of the turbine vane airfoil part, wherein a number of end-side injection holes per unit area is greater than a number of center-side injection holes per unit area, characterised in that a thickness of the wall of the turbine vane airfoil part is gradually increased from the center side to the end side, and the injection holes (712, 714, 722, 724, 730) are formed such that the number of injection holes (712, 714, 722, 724, 730) per unit area is gradually increased from the center side to the end side.