PURPOSE: To use different business menus in the same system and operation method so as to improve work efficiency by storing the various business menus in accordance with a previously decided general-purpose hierarchical rule.

CONSTITUTION: The various business menus are stored in a menu file storage part 6 in accordance with the unified hierarchical rule. When a menu display device is started, a menu display part 7 reads initial menu data from the menu file storage part 6. When a system code is inputted from an input part 1, a system code judgement part 2 selects the concerned menu from the menu file storage part 6 and it is displayed in a display 8. When the menu numbers of the displayed menus are designated, the designated menus are sequentially displayed in the display 8 in accordance with the hierarchical rule through a menu number judgement part 3, the menu file storage part 6 and the menu display part 7.