A boiler includes one or more evaporators configured to heat water which has flowed therein to a specific heat maximum temperature at constant pressure or more in which a specific heat at constant pressure is maximized using a heated fluid and one or more reheaters configured to heat the steam which has come from the boiler using the heated fluid. All the reheaters configured to supply steam to a low-pressure steam turbine are disposed only at a downstream side of the high-pressure evaporator. All the reheaters heat reheating steam (FRHS) containing steam which has passed through a high-pressure steam turbine configured to receive steam supplied from the high-pressure evaporator and having a temperature lower than a specific heat maximum temperature at constant pressure in the high-pressure evaporator to less than the specific heat maximum temperature at constant pressure.
