PURPOSE: To supply water to the surface of a plate cylinder uniformly, continuously, and stably, by interlocking a water stopping chrome roller which is rotated reversely with respect to a water source roller with the water source roller being rotated in a water tank and automatically controlling the water supply to the surface of the plate cylinder.

CONSTITUTION: The water tank 1 which is filled up with water is provided. The water source roller 3 and the water stopping chrome roller 6 are driven. Meanwhile the plate cylinder 9 is driven and a water attaching roller 8 is rotated. The water in the water tank 1 is supplied by the amount of the supplied water 5 (A) of the water source roller 3. The amount is reduced to B by the water stopping chrome roller 6. The same amount C as the amount B is conveyed to the water attaching roller 8 by the rotation of a chrome roller 7. The same amount D as the amount C is supplied to the surface of the plate 10 of the cylinder plate 9. Therefore a specified constant amount (B) of the supplied water 5 of the water source roller 3 is continuously and stably supplied to the surface of the cylinder 10 without change on the way.