A cutting insert has a multi-stage columnar shape with an insert central axis as a center, the cutting insert including: a head portion having a circular cutting edge with the insert central axis as a center, a shaft portion disposed on a lower side of the head portion in an insert axial direction along the insert central axis and having a smaller outer diameter dimension than the head portion; a step portion configured to connect the head portion and the shaft portion; and an index portion disposed over a part of the step portion and a part of the head portion and recessed inward in an insert radial direction from an outer peripheral surface of each of the step portion and the head portion, in which a plurality of the index portions are arranged in an insert circumferential direction, and each of the index portions has a planar alignment surface.

A cutting tool 1 includes a cutting edge 2, a rake face 4 and a flank 5 and is used for cutting a surface of a cylindrical or columnar work W by a skiving process. The cutting tool 1 is configured to satisfy a relational expression:
tan.sup.1(cos /cos()tan.sup.1(cos.sup.1(r/r))<90
where denotes a rake angle, denotes an inclination angle of the cutting edge 2 with respect to the rotation axis A, denotes an angle between a feed direction of the cutting tool 1 and a direction orthogonal to a rotation axis A in a plane view of the cutting tool 1 and the work W, r denotes a radius of an outer circumferential surface of the work W before processing, and r denotes the radius of the outer circumferential surface of the work W after processing.

A cutting tool 1 includes a cutting edge 2, a rake face 4 and a flank 5 and is used for cutting a surface of a cylindrical or columnar work W by a skiving process. The cutting tool 1 is configured to satisfy a relational expression:

tan.sup.1(cos /cos()tan.sup.1(cos.sup.1(r/r))<90

where denotes a rake angle, denotes an inclination angle of the cutting edge 2 with respect to the rotation axis A, denotes an angle between a feed direction of the cutting tool 1 and a direction orthogonal to a rotation axis A in a plane view of the cutting tool 1 and the work W, r denotes a radius of an outer circumferential surface of the work W before processing, and r denotes the radius of the outer circumferential surface of the work W after processing.