Developing device for electrophotographic color copier

A device applicable to an electrophotographic color copier or a color ink jet printer for selectively supplying visualizing liquids of different colors, e.g. black, red, green and blue or a mixture thereof to a photoconductive drum, paper or like recording medium to form a visible image on the medium which corresponds to an image of an original document. The device includes a black liquid vessel, a red liquid vessel, a blue liquid vessel, and a cleaning liquid vessel. The liquids from the various vessels are selectively fed to the device and, after a visualizing operation or a cleaning operation, selectively returned to the respective vessels by two switching units. Residual toner particles are returned to the black liquid vessel. A purifying member for capturing toner or like visualizing agent which is contained in the black liquid is situated between an overflow port of the black liquid vessel and the other liquid vessels and cleaning liquid vessel. Each of the liquid vessels other than the black and cleaning vessel is provided with an overflow port at a slightly higher level than a liquid level upper limit thereof, an effluent vessel communicating to those overflow ports. Another effluent vessel is communicated to the overflow port of the black liquid vessel.