PURPOSE: To surely and easily set the character lowering width of a character string or the end of paragraph by displaying a polygon showing a display range on the character string or the end of paragraph and then performing the setting operation of the character lowering width based on the polygon.

CONSTITUTION: A rectangle/polygon display processing means 14 produces a polygon 20 to show a display range of the selected and 19 of paragraph on a screen and displays the polygone 20 on a character string of the end 19 of paragraph. A rectangle/polygon operating means 15 instructs the change of a character lowering position in response to the operations of a pointing means 18 and a cursor 21. A rectangle/polygon correcting means 16 corrects the coordinates of the polygon 20 based on the notified coordinates of the cursor 21 and displays the corrected polygon 20 on the screen. The coordinates of this displayed polygon 20 is notified to a character string/end-of-paragraph display correcting means 17. Thus the means 17 calculates the set character lowering width based on the notified coordinates of the polygon 20 and then sets a new margin based on the character lowering width. Then the means 17 rearranges the character string of the end 19 of paragraph and displays it on the screen.