A gas turbine cooled stationary blade has a blade structure and outer and inner shrouds enhancing cooling efficiency and preventing the occurrence of cracks due to thermal stresses. A blade (1) wall thickness, between 75% and 100% of the blade height of a blade leading edge portion, is made thicker, and the blade (1) wall thickness of other portions is made thinner, as compared with a conventional case. Protruding ribs (4) are provided on a blade (1) convex side inner wall between 0% and 100% of the blade height. A blade (1) trailing edge opening portion is made thinner than the conventional case. Outer shroud (2) is provided with cooling passages (5a, 5b) for air flow in both side end portions. Inner shroud (3) is provided with cooling passages (9a, 9b) for air flow and cooling holes (13a, 13b) for air blow in the side end portions. With the blade (1) structure and the shroud (2, 3) cooling passages (5a, 5b, 9a, 9b) and cooling holes (13a, 13b), the cooling effect is enhanced and cracks are prevented from occurring.