A character string edition apparatus decides whether the mode is for acquiring a tape width (S301). If the mode is for acquiring the tape width, the tape width of the tape of the cassette mounted on a printer is acquired (S304). According to the acquired tape width, the width of the image of the tape is modified to a width corresponding to the tape width and the tape width is displayed as a tape width displayed in the tape size display area (S309). Thus, it is possible to edit a character string while grasping the sheet size of printing paper filled in the printer.
