Abstract: A cutting insert may include a coupling part, a cutting part, a connection part, a clamping part, and a recess part. Also, the cutting part may include a cutting body part through which the clamping part passes and a cutting edge disposed along an outer circumference of the cutting body part, and the cutting edge may include a main cutting edge provided in plurality to cut the workpiece, a corner cutting edge provided in number corresponding to that of the main cutting edge and extending curvedly from the main cutting edge, a minor cutting edge provided in number corresponding to that of the corner cutting edge and extending from the corner cutting edge to cut the workpiece, and an inclined cutting edge having one end connected to the minor cutting edge and the other end connected to the main cutting edge.