To obtain a display means provided in a control panel or the like where the fault state of the device is always intelligibly displayed on a display screen and informed so as to realize the restoration of the fault state of the device in an earlier stage after simplifying the constitution of the display means and the control panel.

After switching the display screen in every mode, at least explanation concerning operation is displayed in every mode on the display part of the control panel 7 provided in a digital composite machine 1 functioning as a device having a plurality of functional modes (copying, FAX, scanning to E mail or the like). When the function concerning at least one mode out of the plurality of modes can not be used, special display showing that the function which can not be used exists is displayed at least at one part of the screen in the mode displayed at present in order to know the condition of the fault of the digital composite machine 1 quickly. Even when the screen is switched, the special display is continuously displayed.