the eighth commutator segment 72 8 to establish electrical connection therebetween a lead wire 95 engaged with the engaging portion 94 of the commutator segment 72 3 forms the one terminal for the armature winding 70 3 and is wound around the second rotor pole shoe 4 2 formed at the position spaced by an angle of about b u2022 4 u03c0 5 radians in electrical angle from the first rotor pole shoe 4 1 whereby the armature winding 70 3 for the third phase is formed then a lead wire 96 which is contiguous to the wire 95 and forms the other terminal for the third armature winding 70 3 is introduced to an engaging portion 97 of the fourth commutator segment 72 4 to established electrical connection therebetween a lead wire 98 engaged with the engaging portion 97 of the fourth commutator segment 72 4 is then introduced along the lower end face 3a of the rotor armature core 3 to an engaging portion 99 of the ninth commutator segment 72 9 at the same phase position displaced in phase by an angle of 2 u03c0 radians in electrical angle from the fourth commutator segment 72 4 to establish electrical connection therebetween a lead wire 100 engaged with the engaging portion 99 of the commutator.