A gas turbine, a combined cycle plant and a compressor by which both augmentation of the power output and augmentation of the thermal efficiency can be realized by injecting liquid droplets into inlet air introduced into an entrance of a compressor with simple equipment which is suitable for practical use. The gas turbine includes a compressor for taking in and compressing gas, a combustor in which fuel is combusted with the gas discharged from the compressor, and a turbine driven by the combusted gas of the combustor. The gas turbine further includes a liquid droplet injection device provided on the upstream side of the compressor for injecting liquid droplets into inlet air to be supplied into the entrance of the compressor to lower the temperature of the inlet air to be introduced into the compressor so that the injected liquid droplets may be evaporated while flowing through the compressor.