To provide a humid air gas turbine system capable of restraining reduction in exhaust heat usable for a power generation system, even when using the exhaust heat for removing carbon dioxide.

This humid air gas turbine system has a humidifier 7 for humidifying compressed air from a compressor 2, a combustor 4 for burning the air from the humidifier, a turbine 1 rotated by combustion gas from the combustor, an absorbing tower 81 for absorbing the carbon dioxide included in exhaust gas by contacting a liquid phase mixed medium with the exhaust gas from the turbine, a regeneration tower 82 for dissociating the carbon dioxide by contacting a gaseous phase mixed medium with the liquid phase mixed medium from the absorbing tower, an absorbing liquid reheater 83 for heating the liquid phase mixed medium regenerated by the regeneration tower by the exhaust gas of the turbine for generating the gaseous phase mixed medium supplied to the regeneration tower, and a condenser 86 for condensing steam discharged from the regeneration tower by the liquid phase mixed medium discharged from the humidifier. The liquid phase mixed medium heated by the steam by the condenser is used as a heat source for humidifying the compressed air performed by the humidifier.