A cutting insert (10, 100), comprising: a first end surface having an edge portion and including a first surface which is a main surface; a second end surface, which is opposed to the first end surface, having the second surface; and a plurality of cutting edge portions, each of which is formed at an intersection between each end surface and a peripheral side surface which extends between the two end surfaces, the plurality of cutting edge portions being arranged so as to have rotational symmetry about a first axis and rotational symmetry about a second axis (B or C), wherein: an intermediate plane, which is perpendicular to the first axis passing through the first surface and the second surface and passes through the cutting insert, is defined; and the second axis is perpendicular to the first axis and passes through the peripheral side surface, and the second axis extends on the intermediate plane characterized in that: each cutting edge portion includes: a corner edge formed at a corner of a related end surface, the related end surface being the first end surface or the second end surface; a major cutting edge extending from one end of the corner edge, and extending so that a distance between the major cutting edge and the intermediate plane becomes longer than a distance between the main surface of-the related end surface and the intermediate plane; and a minor cutting edge extending from the other end of the corner edge, and extending so that a distance between the minor cutting edge and the intermediate plane becomes shorter than a distance between the main surface of the related end surface and the intermediate plane wherein said major cutting edge extends so as to depart from said intermediate plane with increasing distance from said corner edge, and a major part of the minor cutting edge is formed to be lower than the main surface of the related end surface, in the side view and the front view of the cutting insert. a first end surface having an edge portion and including a first surface which is a main surface; a second end surface, which is opposed to the first end surface, having the second surface; and a plurality of cutting edge portions, each of which is formed at an intersection between each end surface and a peripheral side surface which extends between the two end surfaces, the plurality of cutting edge portions being arranged so as to have rotational symmetry about a first axis and rotational symmetry about a second axis (B or C), wherein: an intermediate plane, which is perpendicular to the first axis passing through the first surface and the second surface and passes through the cutting insert, is defined; and the second axis is perpendicular to the first axis and passes through the peripheral side surface, and the second axis extends on the intermediate plane an intermediate plane, which is perpendicular to the first axis passing through the first surface and the second surface and passes through the cutting insert, is defined; and the second axis is perpendicular to the first axis and passes through the peripheral side surface, and the second axis extends on the intermediate plane each cutting edge portion includes: a corner edge formed at a corner of a related end surface, the related end surface being the first end surface or the second end surface; a major cutting edge extending from one end of the corner edge, and extending so that a distance between the major cutting edge and the intermediate plane becomes longer than a distance between the main surface of-the related end surface and the intermediate plane; and a minor cutting edge extending from the other end of the corner edge, and extending so that a distance between the minor cutting edge and the intermediate plane becomes shorter than a distance between the main surface of the related end surface and the intermediate plane a corner edge formed at a corner of a related end surface, the related end surface being the first end surface or the second end surface; a major cutting edge extending from one end of the corner edge, and extending so that a distance between the major cutting edge and the intermediate plane becomes longer than a distance between the main surface of-the related end surface and the intermediate plane; and a minor cutting edge extending from the other end of the corner edge, and extending so that a distance between the minor cutting edge and the intermediate plane becomes shorter than a distance between the main surface of the related end surface and the intermediate plane said major cutting edge extends so as to depart from said intermediate plane with increasing distance from said corner edge, and a major part of the minor cutting edge is formed to be lower than the main surface of the related end surface, in the side view and the front view of the cutting insert.