Provided is a cutting insert in which cutting edges in a plurality of sections can be used, and it is possible to keep chips, which are discharged from a cutting edge in a section that is being used, from damaging an unused cutting edge in an adjacent section. An edge where an upper surface and a peripheral side surface intersect is divided into a plurality of sections AB, BC, CD, and so on. In each of the plurality of section, the section AB, for example, includes one minor cutting edge and one major cutting edge that is longer than the minor cutting edge. The major cutting edge is inclined at an angle α to be away from a lower surface gradually while extending away from the minor cutting edge. A height position of the upper surface in an up-down direction in which the upper surface and the lower surface oppose each other does not change as the upper surface extends toward the attachment hole, or the height position decreases in a direction from the upper surface toward the lower surface.