DRILLING TOOL

PURPOSE: To reduce frictional resistance on the surface of an ejection path, make the ejection path hard to be choked and enable chips to be ejected smoothly by providing an exciting means for exciting the ejection path through which the chips pass together with a cutting fluid. CONSTITUTION: Ultra sonic wave 54 is generated from an ultra sonic oscillator 2 by operating an oscillating power supply unit 3. After the generated ultra sonic wave 54 is resonated by a born 1, the wall surface of a groove 11c is excited radially of a gun drill 11 through cutting fluid 52 flowing in the groove 11c of the gun drill 11. Thus, the frictional resistance in the groove 11c of the gun drill 11 is reduced substantially to smoothly eject chips 53 flowing in the groove 11c of the gum drill 11. Accordingly, a deep hole in a workpiece 51 can be efficiently accurately worked by the gun drill 11, while the workpiece 51 and gun drill 11 can be prevented from being damaged and broken down.