PURPOSE: To miniaturize a part which displays a density value to be used by using a single density display means for each color when setting each copying density of Y, M, C, and K, selecting one of them, and setting a copying density displayed for the selected color.

CONSTITUTION: When each copying density of the yellow Y, magenta M, cyan C, and black K is set, the single density display means 2 for displaying a copying density of each color is used; one of the Y, M, C, and K is selected as a color of the copying density displayed on the density display means 2, and the copying density displayed for the selected color is set. A CPU 10 controls LEDs 2-6, and resistances 14-18 control current flowing the LEDs 3-6. Thus, a part 2 which displays a density can be miniaturized.