PURPOSE: To provide a power generation system capable of appropriately controlling the relative movement in the axial direction between a steam turbine and a gas turbine.

CONSTITUTION: This power generation system comprises a gas turbine 12, a steam turbine 14 and a generator 16 mounted on a foundation 22 and connected by a single shaft. A thrust bearing 24 is arranged on a single shaft 20 in either of the gas turbine or the steam turbine. Whichever of the gas turbine and the steam turbine contains the thrust bearing is flexibly secured to the foundation, and the remaining gas turbine or steam turbine and the generator are rigidly secure to the foundation. A pair of rigid tie rods extend between the steam turbine and the gas turbine parallel to the shaft to maintain a predetermined axial distance between the turbines, while allowing relative movement in a plane perpendicular to the shaft.