A joint device includes a drive rotor fixed to a drive shaft, a driven rotor fixed to a driven shaft, and a ring-shaped buffer located between the drive rotor and the driven rotor. The drive rotor includes a drive engagement portion that projects toward the driven rotor in an axial direction. The driven rotor includes a driven engagement portion that projects toward the drive rotor in the axial direction. The buffer includes an outer surface, which includes a first engagement recess and a second engagement recess that are recessed toward a radially inner side. An outer diameter of a bottom surface of the second engagement recess is smaller than an inner diameter of the driven engagement portion or an outer diameter of a bottom surface of the first engagement recess is smaller than an inner diameter of the drive engagement portion.