PURPOSE: To efficiently perform detailed monitor and operation due to window display while watching entire display and positioning in the entire display with an original picture.

CONSTITUTION: Concerning the plant integrated control human interface device for monitoring and controlling a plant corresponding to the process flow picture of previously prepared plant summery, this device is provided with an image disk 6 for storing image data showing processes and details, CRT 10 for fetching the relevant image data from the image disk 6 and displaying them on a screen when the information required for monitoring and controlling the plant is designated by a keyboard 26, and image data processing means 21 for respectively identifying the range of a desired partial picture to be displayed by a window concerning the picture displayed on this CRT 10 and the place and size of window display when these factors are designated by mice 27 and 28 and for performing the multi-display of the relevant partial picture showing the details of processes in the designated size at the designated place on the display screen.