PURPOSE: To flatten the torque characteristic of a clutch, and to accurately control the differential limiting force, in an electromagnetic clutch for limiting differential motion, by providing an eccentric groove to the clutch plate on one side, and by making the clutch plate on the other side flat, and also by specifying the surface roughness of both the clutch plates.

CONSTITUTION: A multiple disk electromagnetic clutch for limiting the differential motion of the differential mechanism of a differential gear is made up of an outer plate 75 and an inner plate 77, and the outer plate 75 is connected to the internal gear by a spline 79, and the inner plate 77 is connected to the cam ring by a spline 81. In this case, the outer plate 75 is formed into a flat shape, while the inner plate 77 is provided with an eccentric groove 113. The flatness of the respective plates 75, 77 is made to be 0.15μm or less, and the surface roughness thereof is made to be 5μm or more, and also the surfaces of the respective plates 75, 77 are subjected to carburizing hardening. Thereby, the oil retaining quantity between the plates 75 and 77 is reduced, and also the magnetic resistance is reduced.