PURPOSE: To efficiently and accurately perform spread working a hole formed in a metal material by providing a guide part, having a cylindrical margin with a rotary lotus in the axial direction of equal diameter to a maximum diametric part of a point end cutting edge, in a specific width along a shaft of an edge part in the peripheral surface thereof in a point end side of the reamer cutting edge part.

CONSTITUTION: In the point end side of a reamer cutting edge part L2, a guide part L4, having a cylindrical margin with a rotary locus in the axial direction of this reamer cutting edge part in diameter equal to a maximum diametric part of a point end cutting edge 16, is provided in a specific width along a shaft of an edge unit 15a. As a result, a rear end of the point end cutting edge 16 is connected to the reamer cutting edge part L2 by the guide part L4. Here is set a maximum diameter d2 of the rotary locus of the point end cutting edge 16 smaller than a maximum diameter d1 of the rotary locus of a reamer cutting edge 19 in diameter by (about 0.004-0.03) d1.