An electromagnetic clutch that can be easily miniaturized in a direction of a rotational axis of the clutch comprises a driven gear adapted to be rotatably driven by a motor; a rotor rotatable with the rotational axis that is shared with the driven gear and having an electromagnetic coil provided at one end thereof along the rotational axis; an armature mounted between the driven gear and the rotor to be rotatable in unison with the driven gear, and attracted by the rotor when current is applied to the electromagnetic coil; a clutch case accommodating the driven gear, the rotor and the armature therein; a pair of slip rings mounted on one of the rotor at a region adjacent the clutch case that faces away from the armature, and the clutch case at a region adjacent the rotor; the pair of slip rings being coaxial with the rotational axis and having different radii; and a pair of brush elements mounted on the other of the rotor and the clutch case to come into contact with the pair of slip rings from a radial direction, respectively.