PURPOSE: To enable feeding water without pulsation by providing a pulsation eliminating tank provided with a water reservoir and an air chamber adjacent to the water reservoir, opening a discharge passage of a pump in the air chamber, and connecting a water feed passage to the water reservoir to feed water.

CONSTITUTION: Water discharged from a pump 2 is discharged into an air chamber 1B of a pulsation eliminating tank 1 through a discharge passage 3, becomes small droplets 6, and drops into a water reservoir 1A. Thus, pulsation inherent to the pump 2 is eliminated by changing water into droplets 6. On the other hand, the air chamber 1B functions as a pressure storage chamber to pressurize the surface of stored water and feeds water without pulsation under pressure into an injection nozzle 5 through a water feed passage 4. Consequently, it is possible to jet the water which does not cause fluctuation of pressure which accompanies pulsation inherent to the pump 2 from the nozzle 5. Also, it is possible to eliminate pulsation by forming a thin water film 8 by making discharged water collide against a ceiling 7 of the air chamber 1B.