To improve tool rigidity by fitting a plural number of one kind of tip.

Two identical tips 7A, 7B are opposingly fitted to the end of a tool body with an axis O in between them. Respective tips 7A, 7B are provided with a long cutting tooth 13 as a face cutting tooth projecting to the end of the tool body 2, an acute angled first corner 18 positioning on the outer side of the long cutting tooth 13, and a first cutting blade 15 forming an outer circumferential blade. The long cutting tooth 13 is inclined to the base end side from the outer circumferential side toward the inside because the first cutting blade 15 is arranged along the outer circumferential surface 2b of the tool body 2. A second cutting blade 16 continued to a third corner 20 of an obtuse angle on the inner end on each long cutting tooth 13 is inclined from the end side towards the base end in the direction of separating from an axis O. Therefore the end center 22 of the tool body 2 sandwiched between both tips 7a, 7B becomes gradually thicker towards the base end side.