To inhibit maximum transmittable torque from decreasing by making all groups of protrusions and recesses making up an eccentric joint contact each other while transmitting power even if dispersion and the like exist in errors.

The eccentric joint 41 is made up of conical tapered rollers 42 provided protrusively on a rotating body 15a and conical cavities 43 provided in another rotating body 32 in such a way that the conical tapered rollers 42 are fitted loosely. The conical tapered rollers 42 are of a conical shape tapered toward the rotating body 32, while the conical cavities 43 are of a conical shape expanded toward the rotating body 15a. When the conical taper rollers 42 are provided protrusively on the rotating body 15a, drive pins 44 are used. These drive pins 44 penetrate the rotating body 15a rotatably and in such a way as to enable displacement in axial direction. The conical tapered rollers 42 are fixed at the end of the drive pins 44 near the rotating body 32. The conical tapered rollers 42 are kept in a state of being in contact with the conical inside circumferential surface of the conical cavities 43 by an elastic member 47.