To efficiently suppress chattering vibration of cutting edges to improve the durability and the facing accuracy.

Both tips 17, 18 fixed to the tip part 15 of a shank, are provided symmertrically in diametrically opposite directions. Further, respective cutting edges 19, 20 of both the tips have the first cutting edge parts 19a, 20a for cutting small diameter tapered surfaces on the tip side, and are provided with the second cutting edge parts 19b, 20b by which large taper angles are formed in succession to the end edges of the respective first cutting edge parts. Furthermore, the third cutting edge parts 19c, 20c for cutting holes of the largest diameter, the diameter of each of which is larger than that of the shank 12 and which are vertical, are provided integrally on the end edges of the respective second cutting edge parts.