A rotation transmission device is provided in which a collision sound by an armature and a rotor is less likely to occur, and further the armature is stably attracted to the rotor. A buffer is provided between the armature and the rotor. The buffer is constituted by a metal annulus axially movably supported by the armature, and a rubber annulus configured such that as the armature approaches the rotor, the rubber annulus is axially compressed by the metal annulus and the armature. The rubber annulus has different axial thicknesses at different circumferential locations thereof such that when the degree of axial compression of the rubber annulus is large, the rubber annulus is axially compressed in its longer circumferential area than when the degree of axial compression of the rubber annulus is small.