In the present invention, a coal gasification combined power generation facility comprises: a feed water supply line (72); a condensate pump (39) and an intermediate-pressure feed water pump (40); a turbine bypass line (32) that bypasses a steam turbine and supplies steam to the condenser (73); and a spray water line (76) that supplies the feed water to the turbine bypass line (32). The coal gasification combined power generation facility has a normal operation mode and a bypass operation mode, and in the bypass operation mode, a control device (80) supplies the feed water to the turbine bypass line (32) and performs a first opening degree control to control the opening degree of the supply adjustment valve so that the amount of feed water supplied to the exhaust heat recovery boiler becomes less than that in the normal operation mode.