To prevent vibration caused by jetting pressure of damping water from being generated and to simplify mechanism.

In a spray type damping water feeding apparatus which jets and feeds damping water to the face of a printing plate or the peripheral face of rollers reaching the printing plate of an offset rotary press, a water jetting means B for jetting the damping water in such a way that dimensions of spray patterns S intersecting at right angles each other in two directions are different on a plane crossing the jetting direction at right angles, a rotating means C displacing angularly the water jetting means around the central line of water jetting, an insulating means D provided by being fixed on the machine body side in such a way that an opening 14 is formed at the front of water jetting direction of the water jetting means and an interval between at least two facing edges of this opening is smaller than the dimension of the longer direction of the above described spray pattern of the damping water jetted from the water jetting means and is larger than the dimension of the shorter direction, are provided.