To easily confirm differences in correction place and font by comparing character data matching a font and displaying different character data on a display means according to the comparison result.

A CPU 1 refers to character management information belonging to a selected font to be compared, refers to character data on a specified character, and compares the character data which are referred to. On a keyboard 5, the font to be compared and its version are specified. The character data are displayed on a CRT display device 7. An external storage device 9 stores a character data comparison program and relative data. Then a display control part 6 displays different character data on the CRT display device when the comparison result indicates a difference. Therefore, pieces of character information on, for example, a character pattern and a character feed quantity etc., at the time of printing can be compared and displayed and differences in correction place and font can easily be confirmed.