PURPOSE: To prevent erroneous setting by perfroming the setting operation of attribute information to varibale graphic parts from a window for setting displayed on a plant monitoring screen at the time of preparing the plant monitoring screen and thereby enabling attribute information setting operation while directly looking at the plant monitoring screen.

CONSTITUTION: Extension is performed on display tables for respective screens by an automatic generation program 4 based on setting data such as color specification and flikker conditions, etc., inputted by a CRT setting screen display program 2 to the variable graphic parts such as symbols or the like within the plant monitoring screen prepared by the function of a CRT device beforehand. At this time, the CRT setting screen display program 2 window- displays a setting screen for setting the attribute information to the variable graphic parts on the plant monitoring screen. Then, after screen preparation operation is completed, when displaying the plant monitoring screen, a CRT display program 6 refers to the display tables for the screens and displays the screen.