PURPOSE: To enable the removal of chip in a machined hole at the time of boring by forming one jet hole or more opened outward while communicating the cylindrical inner surface, and a fluid feeding hole part communicated with a hollow part from the flange part outer side face on the flange part end face side.

CONSTITUTION: A ring like hollow part 3 is provided in a flange part 2. One jet hole 4 or more opened outward while communicating the cylindrical inner surface 8, and a fluid feeding hole 5 communicated with the hollow part 3 from the flange part outer side face 9 are formed on the flange part end face 10 side. A cutout part 7 for locking a jig bush 1 to a machining jig 12 through a fixing member 13 is provided in a position not interfering with the hollow part 3, fluid feeding hole 5 and jet hole 4 of the flange part 2. The opening part of the jet hole 4 is used as a nozzle to the outside, and washing liquid or the like is discharged from this part to wash the inside of a non-through hole 16, thus removing chip in the hole 16.