PURPOSE: To obtain copies in difference colors easily by one copying machine and to obtain a copy in a desired color correctly by displaying the color of stored toner outside of a main body when the main body is equipped with a developing device.

CONSTITUTION: When one main body is equipped with developing devices 8B, 8M, and 8Y, responding members are provided to the main body and developing devices. In this case, three microswitches B, M, and Y are provided to the main body side as said members and when three developing devices 8B, 8M, and 8Y are attached to the main body alternatively, the developing devices 8B, 8M, and 8Y have members 15B, 15M, and 15Y which operate on the switches B, M, and Y. Consequently, when a toner storage developing device BB of color B is attached to the main body, the lamp B of a toner color display panel provided at the console panel position of the main body turns on by the operation of the switch B. When the developing devices 8M and 8Y are attached, the switches M and Y are turned on similarly to turn on pilot lamps M and Y, respectively.