PURPOSE: To provide a centering rod and a perforating drill capable of attaching the centering rod to the perforating drill without necessitating various kinds of adapters having different outside diameters and improving the workability in attaching/detaching of the centering rod to/from the perforating drill.

CONSTITUTION: In a centering rod 1 positioned coaxial with a blade in its attaching to an external thread 12 and attachably/detachably protruded from the external thread 12 for attaching the blade of a perforating drill 2 from which the blade is detached, a recessed part 22 whose inside diameter is formed slightly smaller than the outside diameter of the external thread 12, and through which the external thread 12 is loosely inserted is provided on one end side, and a protrusion 35 to be slidably fitted along the valley of the external thread 12 is formed on the inner peripheral surface on the way in the axial direction.