Cutting insert and cutting tool equipped with cutting insert

A cutting insert which is capable of being mounted on a body of a cutting tool, the cutting insert comprising:

• First constraining surfaces, which are a pair of surfaces facing each other in a rotating direction of the body, and one of which is constrained by the body;
• second constraining surfaces, which are a pair of surfaces facing each other in a direction toward a rotational center axis of the body, and one of which is constrained by the body;
• cutting edges disposed respectively along a pair of sides, which extend from one of the second constraining surfaces to the other of the second constraining surfaces and are located at positions facing each other, of sides framing the first constraining surface;
• and
• flanks which are disposed at positions adjacent to the cutting edges respectively in the rotating direction, wherein
• an angle formed by the first constraining surface and the flank, which are adjacent to each other across the cutting edge, is larger than 90°.