An indexable rotary cutting tool comprising: a substantially cylindrical tool body having a rotational axis; and cutting inserts mounted on the tool body, in which a plurality of grooves is formed in a peripheral surface of the tool body, a plurality of insert seats is formed in the grooves, and the cutting inserts are removably arranged onto the insert seats, wherein: the cutting inserts each have a rake surface and a flank intersecting with the rake surface, and a major cutting edge, a corner cutting edge connected to the major cutting edge, and a minor cutting edge connected to the corner cutting edge, are formed in an intersecting edge between the rake surface and the flank; the major cutting edge is formed along each side of the rake surface of the cutting insert and is in a wave shape as viewed from a direction facing the rake surface and the cutting inserts are arranged such that, in rotational trajectories formed by the major cutting edges of the respective cutting inserts when the indexable rotary cutting tool is rotated around the rotational axis, phases of waves of rotational trajectories formed by cutting inserts that are adjacent to each other in a direction along the rotational axis in one groove coincide with each other, and such that at least some of the cutting inserts are arranged such that, from among the rotational trajectories formed by the major cutting edges, rotational trajectories formed by part of cutting edge portions are overlapped with each other in a direction of the rotational axis, wherein the major cutting edge is formed in a wave shape having a plurality of outwardly-curved cutting edge portions that are curved outwardly as viewed from the direction facing the rake surface; and characterised in that in each of the grooves, the at least some cutting inserts are arranged such that, from among the rotational trajectories formed by the major cutting edges, only rotational trajectories formed by outwardly-curved cutting edge portions located closest to ends of the major cutting edges are overlapped with each other in the direction of the rotational axis and, wherein: in the plurality of outwardly-curved cutting edge portions, an outwardly-curved cutting edge portion located at an end of the major cutting edge and connected to the minor cutting edge is configured to also serve as an inner cutting edge. the cutting inserts each have a rake surface and a flank intersecting with the rake surface, and a major cutting edge, a corner cutting edge connected to the major cutting edge, and a minor cutting edge connected to the corner cutting edge, are formed in an intersecting edge between the rake surface and the flank; the major cutting edge is formed along each side of the rake surface of the cutting insert and is in a wave shape as viewed from a direction facing the rake surface and the cutting inserts are arranged such that, in rotational trajectories formed by the major cutting edges of the respective cutting inserts when the indexable rotary cutting tool is rotated around the rotational axis, phases of waves of rotational trajectories formed by cutting inserts that are adjacent to each other in a direction along the rotational axis in one groove coincide with each other, and such that at least some of the cutting inserts are arranged such that, from among the rotational trajectories formed by the major cutting edges, rotational trajectories formed by part of cutting edge portions are overlapped with each other in a direction of the rotational axis, wherein the major cutting edge is formed in a wave shape having a plurality of outwardly-curved cutting edge portions that are curved outwardly as viewed from the direction facing the rake surface; and characterised in that in each of the grooves, the at least some cutting inserts are arranged such that, from among the rotational trajectories formed by the major cutting edges, only rotational trajectories formed by outwardly-curved cutting edge portions located closest to ends of the major cutting edges are overlapped with each other in the direction of the rotational axis and, wherein: in the plurality of outwardly-curved cutting edge portions, an outwardly-curved cutting edge portion located at an end of the major cutting edge and connected to the minor cutting edge is configured to also serve as an inner cutting edge.