A cutting insert enables a reduction in cutting resistance and stable cutting process. The insert includes a chip breaker groove formed inside corner cutting edges and a raised portion. The raised portion includes a top surface, a front raised surface, and side raised surfaces. The top surface intersects the front raised surface and each of the side raised surfaces. A first intersecting portion at which the front raised surface and the top surface intersect with each other extends linearly. A second intersecting portion at which each of the side raised surfaces and the top surface intersect with each other extends from a corresponding one of opposite sides of the first intersecting portion so that a distance from the corresponding side cutting edge increases gradually with a distance from the corner cutting edge. The front raised surface and the side raised surfaces are curved convexly outward.