PURPOSE: To promptly display a help screen corresponding to a current processing screen by providing a help process which displays a further detailed screen corresponding to selection from the help screen independently of a processing system process.

CONSTITUTION: A help process 5 independently provided of the processing system process consists of a parameter analyzing part 6, a help screen display part 7, a menu display/selecting function analyzing part 8, a help contents display/ selecting function analyzing part 9, a help main control processing part 5-1, etc. According to the selection of the display of a help screen 2 from the screen, the help screen 2 corresponding to the identifier of a processing screen 1 is displayed as well, and the further detailed help screen 2 corresponding to the selection from the help screen 2 is displayed or the process is returned to the processing screen 1. Thus the help screen 2 corresponding to the current processing screen 1 can be promptly displayed by a simple operation.