PURPOSE: To provide a copying water-treating device capable of preventing color unevenness and mixing of colors, etc., that could be caused by splashing of water to the phosphor screen of a cathode-ray tube during the process of water-treating which is required to form the phosphor screen.

CONSTITUTION: The panel 1 of a cathode-ray tube is rotatably installed. The outer peripheral face 4b of the skirt portion 4 of the panel 1 is guided by guide rollers 5, 6 whose ends have an angle of not more than 90 degrees. The guide rollers 5, 6 are shifted toward respective axes 14, 15 of rotation and are so disposed that the interval S between the axes 14, 15 of rotation is smaller than the diameter D of each of the guide rollers 5, 6. Treating water W is supplied to the inner peripheral face 4a of the skirt portion 4 of the panel 1 from a nozzle 8. The guide rollers 5, 6 are operated in conjunction with the nozzle 8.