To provide a control panel capable of coping with a new function by replacing a cover member, by disposing a selection button for the optional function as a spare, in addition to providing a function for a FAX and a copy machine as a basic function in a function selecting part provided in the composite machine of an image forming device.

The function selecting part 10 is disposed on the control panel 1 provided in the composite machine of the image forming device in addition to normal ten keys and abbreviated dial keys, in order to select one from a large number of functions. Although selection buttons 11, 12... are prepared in advance in the function selecting part 10, in the first place, buttons 11, 12 for two functions of a FAX and a copy machine are exposed from punched holes provided in a cover member 20. When assembling an additional function, the cover member corresponding to the number of functions is mounted as a replacement so that an optional function can be easily selected.