PURPOSE: To improve the operability of a display device having a window display function.

CONSTITUTION: When a window display is instructed, a cell (or each small area of display screen divided into plurality of small areas) farthest from a cursor position P is retrieved and selected, and a window is opened about the center position of the cell. In this case, a window display position is shifted in consideration of display screen and window sizes, so that the opened window will be kept within the display screen of CRT 3. According to this system, the window is displayed at a position farthest from the cursor, or in the minimum area of information display and, therefore, an operation such as in document edition is not interrupted by the window.