A gas turbine system includes: a compressor configured to compress external air to generate compressed air; a combustor configured to burn the compressed air together with fuel to generate a combustion gas; a turbine configured to be driven by the combustion gas; an exhaust unit configured to guide the combustion gas, which has passed through the turbine, to outside; a shell having a cylindrical shape and extending along an axis line about which the turbine is configured to rotate and being arranged so as to cover the compressor, the combustor, the turbine, and the exhaust unit; and an exit unit configured to guide the combustion gas, which has passed through the turbine, to a discharge port in the surface of the shell.