Abstract: Provided is a gas turbine system capable of dealing with a request for output increase even when high-pressure hot water generated using solar thermal energy cannot be used according to the operating state of the gas turbine system. A gas turbine system which sucks in intake air from an air intake duct by a compressor and drives a gas turbine by combustion gas obtained by burning air and fuel by a combustor, said gas turbine system being provided with pipes for generating high-pressure hot water by providing a solar collecting tube that utilizes solar heat and spraying the high-pressure hot water into the intake air sucked in by the compressor, and pipes for spraying normal temperature water into the intake air sucked in by the compressor.