PURPOSE: To prevent a radio wave noise generated by a spark from leaking by bending the end of a conductive brush holder at a commutator side to the opposite side to brushes to so form a bevel as to cover the contact of the brushes with the commutator.

CONSTITUTION: A current flows from a brush 22 through the contact of the brush with a commutator 24 to the commutator 24, a rotor 23. A spark of a commutation is generated at the contact of the brush 22 with the commutator 24 at this time. A radio wave noise is generated from the spark to tend to externally scatter, but since the outer periphery is covered with the bevel 21a of a brush holder 21 made of a conductive material, it is in contact with the bevel 21a to be reflected or absorbed, thereby interrupting most of the noise at the inside.