Steam cooled turbine

The steam-cooling-type gas turbine is provided with communication passages in number equal to that of the front-stage stator blades and the rear-stage stator blades. Many communication passages are placed in the blade ring densely. As a result, in the blade ring, the temperature difference between the portion having the communication passages and the portion without the communication passages becomes smaller. This makes it possible to minimize the thermal deformation of the blade ring, thereby making it possible to provide uniform clearance between the fixed side such as the blade ring and the rotary side members.