PURPOSE: To reduce the leakage flux and improve the transmission torque and reduce dimension and secure the low consumption of electric power by interposing a nonmagnetic member having a small magnetic permeability between a clutch rotor and an output shaft and between the edge surfaces of the clutch rotor and a flange.

CONSTITUTION: A plain bearing 24 made of nonmagnetic material is installed between a clutch rotor 6 and an output shaft 10, and supports the clutch rotor 6. A washer 25 made of nonmagnetic material is installed between the edge surfaces of the clutch rotor 6 and a flange 9. Therefore, the leakage flux is reduced, and the transmission torque is improved, and the small-sized electromagnetic clutch can be obtained, and the low consumption of electric power is secured.