An electromagnetic coupling comprises a stator, a first rotor in which a first polar tooth and a second polar tooth are provided along a circumferential direction in an alternating manner, and a second rotor. The first rotor comprises a first polar tooth ring in which a plurality of the first polar teeth are provided along a circumferential direction with a gap therebetween, and a second polar tooth ring in which a plurality of the second polar teeth are provided along a circumferential direction with a gap therebetween, and which is placed opposing the first polar tooth ring such that the second polar teeth are placed in respective gaps between adjacent ones of the first polar teeth.