A rotor (11) is provided with: a main permanent magnet mounting layer (21) having a plurality of main permanent magnets (21a) mounted thereon; a first sub permanent magnet mounting layer (22) having a plurality of first sub permanent magnets (22a) mounted thereon; a second sub permanent magnet mounting layer (23) having a plurality of second sub permanent magnets (23a) mounted thereon; and a phase change mechanism capable, by turning at least either one of the first sub permanent magnet mounting layer (22) and the second permanent magnet mounting layer (23), and the main permanent magnet mounting layer (21) about the rotational axis, of changing the relative phase between the first sub permanent magnet mounting layer (22) and the second permanent magnet mounting layer (23), and the main permanent magnet mounting layer (21).