To provide a power generation system that prevents a reduction in the efficiency of a steam turbine due to an aperture adjustment of a turbine governing valve. There is provided a power generation system comprising: a furnace in which a solid fuel or a liquid fuel is combusted; a steam turbine that generates electric power by rotating a turbine rotor using steam generated by the furnace; a superheater that is provided between the furnace and the steam turbine and that superheats the steam; a first steam piping that connects the furnace to the superheater; a second steam piping that connects the superheater to the steam turbine; a first valve provided in the first steam piping; a turbine governing valve provided in the second steam piping; and a control section that adjusts an aperture of the first valve according to a load of the steam turbine.