PURPOSE: To enable smooth monitoring by obtaining an optimum color scheme of an information screen corresponding to a plant state.

CONSTITUTION: This device is equipped with a display 1, a data input device 3 which inputs a display request, etc., from an operator, a color scheme data base 5 wherein data on optimum design of a background and a character color are registered, a color design data base 7 wherein color variation data prescribing color variation of the screen at the time of a state change of the plant and screen management data showing the importance of the screen are registered, a screen management means 11 which performs the selection of proper screen colors for the plant state and screen management corresponding to the use state of the operator by using the color design data base 7 and outputs a request to change colors of an output screen, etc., and an information output means 9 which arranges colors on the information screen by referring to the color scheme data base 5 at an operator's display request or a request to change colors or erase the screen from the screen management means 11 and outputs it so that the screen can be superimposed on the display 11.