GAS TURBINE

This gas turbine includes a turbine cooling structure of cooling a turbine by using cooling air and a filter that reduces dust in the cooling air on an upstream side of the turbine. Furthermore, the gas turbine includes a supply pipe for supplying the cooling air to the filter, a branch pipe that is branched from the supply pipe on an upstream of the filter, and a unit that calculates or estimates a circulation amount of dust in the cooling air. In this gas turbine, at a time of start-up of a turbine, the supply pipe is closed and the branch pipe is opened, and when the circulation amount of dust in the cooling air becomes equal to or less than a predetermined threshold, the supply pipe is opened and the branch pipe is closed.