A humid air turbine comprising: a compressor configured to compress air to generate compressed air; a moisture system configured to supply moisture to intake air of the compressor or the compressed air generated by the compressor; a combustor configured to mix humid air generated by supplying the moisture to the intake air or the compressed air with a fuel and to combust the mixture to generate combustion gas; a fuel supply system, having a fuel flow rate control valve, configured to supply the fuel to the combustor; a turbine configured to be rotationally driven by the combustion gas supplied from the combustor; an exhaust temperature acquiring unit for acquiring an exhaust temperature that is a temperature of exhaust discharged while the turbine is driven; and a controller comprising a pressure ratio calculating section configured to calculate a pressure ratio of the compressor and a combustion gas moisture ratio calculating section configured to acquire a combustion gas moisture ratio that is a ratio of moisture contained in the combustion gas; wherein the humid air turbine is characterized in that the controller further comprises: an exhaust temperature upper limit calculating section configured to calculate an upper limit for the exhaust temperature based on the combustion gas moisture ratio and the pressure ratio; and a control command value output section configured to output a command signal to the fuel flow rate control valve using a fuel flow rate command value calculated based on the exhaust temperature upper limit calculated by the exhaust temperature upper limit calculating section and on the exhaust temperature. a compressor configured to compress air to generate compressed air; a moisture system configured to supply moisture to intake air of the compressor or the compressed air generated by the compressor; a combustor configured to mix humid air generated by supplying the moisture to the intake air or the compressed air with a fuel and to combust the mixture to generate combustion gas; a fuel supply system, having a fuel flow rate control valve, configured to supply the fuel to the combustor; a turbine configured to be rotationally driven by the combustion gas supplied from the combustor; an exhaust temperature acquiring unit for acquiring an exhaust temperature that is a temperature of exhaust discharged while the turbine is driven; and a controller comprising a pressure ratio calculating section configured to calculate a pressure ratio of the compressor and a combustion gas moisture ratio calculating section configured to acquire a combustion gas moisture ratio that is a ratio of moisture contained in the combustion gas; wherein the humid air turbine is characterized in that the controller further comprises: an exhaust temperature upper limit calculating section configured to calculate an upper limit for the exhaust temperature based on the combustion gas moisture ratio and the pressure ratio; and a control command value output section configured to output a command signal to the fuel flow rate control valve using a fuel flow rate command value calculated based on the exhaust temperature upper limit calculated by the exhaust temperature upper limit calculating section and on the exhaust temperature. an exhaust temperature upper limit calculating section configured to calculate an upper limit for the exhaust temperature based on the combustion gas moisture ratio and the pressure ratio; and a control command value output section configured to output a command signal to the fuel flow rate control valve using a fuel flow rate command value calculated based on the exhaust temperature upper limit calculated by the exhaust temperature upper limit calculating section and on the exhaust temperature.