A commutator including commutator segments each having a stepped portion formed at the bottom of a slot which is formed at one end of the commutator segment and into which portions of armature coils are inserted, to prevent axial escapement of the armature coils. A lower coil of the armature coils is plastically deformed to conform to the contour of the stepped portion and outer surface of an upper coil of the armature coils is plastic-deformed together with the commutator segments by pressing the edge of the opening of the slot to couple the armature coils to the commutator segments.
