A gas turbine combustor by-pass valve device comprises an air by-pass duct (015) and a by-pass valve (08) provided in an inlet portion of the air by-pass duct (015) to be opened and closed by rotation of a drive shaft (09). A perforated plate (41) is provided on a front side or on a back side of the by-pass valve (08). This prevents foreign matter from entering the by-pass valve and reducing its performance and it avoids damage to the moving and stationary blades of the gas turbine. <IMAGE>
