There is provided a combined cycle power plant in which a high-pressure steam turbine and an intermediate-pressure steam turbine can operate in a state where amounts of thermal effect thereof are close to a limit value, and capable of reducing start-up time. A combined cycle power plant includes: an exhaust heat recovery boiler that includes a high-pressure superheater which superheats steam for a high-pressure steam turbine, and a reheater which reheats steam for an intermediate-pressure steam turbine; bypass pipes through which steam bypasses the high-pressure superheater and the reheater; bypass valves that regulate flow rates of steam which flows through the bypass pipes; and a bypass controller that controls the bypass valves such that a difference between thermal effect-amount margins of the turbines is decreased.