A ridgeline between the top surface and the side surface includes: a nose cutting edge portion having a curved line shape, the nose cutting edge portion having a first end and a second end opposite to the first end; a major cutting edge portion contiguous to the first end; and a wiper cutting edge portion contiguous to the second end. The top surface includes: a first rake face contiguous to the wiper cutting edge portion; a second rake face contiguous to the major cutting edge portion; and a third rake face contiguous to the nose cutting edge portion and contiguous to each of the first rake face and the second rake face. A boundary line between the second rake face and the third rake face is separated from the first end and is contiguous to the major cutting edge portion.

A cutting insert includes a main body including a first face, a second face, and a third face. The second face includes a rake face. Among the outer-peripheral sides of the second face, the boundary portion with the first face is a main cutting edge. When viewed from the side where the first face is disposed, the main cutting edge includes a first straight portion, a second straight portion, and a curved portion. The first straight portion is located adjacent to a reference side. The second straight portion is arranged at a distance from the first straight portion. The curved portion connects the first straight portion and the second straight portion. A first intersection angle of the first straight portion with respect to the reference side is different from a second intersection angle of the second straight portion with respect to the reference side.

A cutting insert includes a main body including a first face, a second face, and a third face. The second face includes a rake face. Among the outer-peripheral sides of the second face, the boundary portion with the first face is a main cutting edge. When viewed from the side where the first face is disposed, the main cutting edge includes a first straight portion, a second straight portion, and a curved portion. The first straight portion is located adjacent to a reference side. The second straight portion is arranged at a distance from the first straight portion. The curved portion connects the first straight portion and the second straight portion. A first intersection angle of the first straight portion with respect to the reference side is different from a second intersection angle of the second straight portion with respect to the reference side.

A cutting insert includes a main body including a first face, a second face, and a third face. The second face includes a rake face. Among the outer-peripheral sides of the second face, the boundary portion with the first face is a main cutting edge. When viewed from the side where the first face is disposed, the main cutting edge includes a first straight portion, a second straight portion, and a curved portion. The first straight portion is located adjacent to a reference side. The second straight portion is arranged at a distance from the first straight portion. The curved portion connects the first straight portion and the second straight portion. A first intersection angle of the first straight portion with respect to the reference side is different from a second intersection angle of the second straight portion with respect to the reference side.

A ridgeline between the top surface and the side surface includes: a nose cutting edge portion having a curved line shape, the nose cutting edge portion having a first end and a second end opposite to the first end; a major cutting edge portion contiguous to the first end; and a wiper cutting edge portion contiguous to the second end. The top surface includes: a first rake face contiguous to the wiper cutting edge portion; a second rake face contiguous to the major cutting edge portion; and a third rake face contiguous to the nose cutting edge portion and contiguous to each of the first rake face and the second rake face. A boundary line between the second rake face and the third rake face is separated from the first end and is contiguous to the major cutting edge portion.

A cutting insert includes first and second polygonal surfaces and a plurality of side surfaces. A corner edge that has a corner rake surface on the first polygonal surface is formed at a first corner portion, and a main cutting edge is formed from the corner edge to a second corner portion. The main cutting edge includes, at least on a corner edge side, a rake angle gradual increase region where a rake angle of a main rake surface gradually increases to a positive angle side as going from a first end portion of the corner edge toward a second corner portion side.

A cutting insert includes a main body including a first face, a second face, and a third face. The second face includes a rake face. Among the outer-peripheral sides of the second face, the boundary portion with the first face is a main cutting edge. When viewed from the side where the first face is disposed, the main cutting edge includes a first straight portion, a second straight portion, and a curved portion. The first straight portion is located adjacent to a reference side. The second straight portion is arranged at a distance from the first straight portion. The curved portion connects the first straight portion and the second straight portion. A first intersection angle of the first straight portion with respect to the reference side is different from a second intersection angle of the second straight portion with respect to the reference side.