To reduce attraction sound of an armature, prevent wrong operation of the armature and improve the durability of a damper rubber.

A damper rubber 15 is stored in a damper rubber storing part 16 provided on the flange 10 of an armature hub 11. At least the inside of the outer periphery edge of the head 18b of a pin 18 with head penetrated a pin main body 18a in the insertion hole 24 of the damper rubber is formed into an arc-shape part 40. A cylindrical projection 25 is integrally provided on the opening edge of the insertion hole of the damper rubber. A surface 41 which retreats in the axial direction, going toward the outside is formed on the diametrical direction outside of the surface which faces the head of the damper rubber.