Abstract: A plant condition display system for displaying items of information regarding a plant operation for an operator comprises a process signal input device into which process values are inputted from a plant and converted therein into process signals, a display data preparation device for preparing data for displaying plant conditions in response to the process signals from the process signal input device, and a plant condition information display device for representing process information of the plant in accordance with plant condition display data from the display data preparation device and then displaying the represented process information on a display screen. The plant condition information display device is a display device for displaying plant start up conditions or a decay heat removal operation condition during a plant shutdown.