Abstract: An insert includes an upper surface, a lower surface, lateral surfaces, a cutting edge, and a through hole. The upper surface includes a first corner having a protruding curve shape and a first side and a second side extending from the first corner. A first region of a first lateral surface has a recessed shape recessed toward an axis. The upper surface further includes a recessed portion that is located between the second side and the axis and is recessed toward the axis. An entirety of the recessed portion is located farther from the first corner than an entirety of the first region in a direction along the axis.

Abstract: An insert includes a first part and a second part. The first part includes a first surface, a second surface, and a plurality of side surfaces located between the first surface and the second surface. The second part includes a third surface, a fourth surface, and a first cutting edge. The third surface is located between the side surfaces and located from a side of the first surface to a side of the second surface. The fourth surface is located between the side surfaces and adjacent to the third surface. The first cutting edge is located along at least a part of a ridge line of the third surface and the fourth surface. The first cutting edge is inclined in a front view of the third surface, and the first cutting edge has a convex curvilinear shape in a front view of the fourth surface.