When a rotating electric machine such as a brushed DC motor is operated, electromagnetic noise is generated due to sliding contact between a brush and a commutator. The noise is superimposed on, for example, a casing (motor yoke), a power-supply terminal and a wire harness which are provided in the rotating electric machine, and the noise may cause electromagnetic interference to peripheral equipments. Generally, a noise cancelling element such as a capacitor or a choke coil is provided in an electric circuit in order to reduce the noise and eliminate the electromagnetic interference to the peripheral equipments, for example, in Patent Document 1 (JP 2012-514966 A). In Patent Document 1, an inductor (choke coil) is arranged between a brush and an electric wire, and a capacitor is arranged between terminals of two brushes.
Such a noise reducing mechanism using the noise cancelling element is capable eliminating noise having a frequency lower than or equal to hundreds of MHz, but it may be difficult to eliminate noise having a frequency within a frequency range higher than hundreds of MHz. Accordingly, it may be difficult for the conventional noise reducing mechanism to eliminate the high-frequency noise. Thus, the high-frequency noise may transmit to a casing, a power-supply terminal and a wire harness sequentially, and may radiate in air. As a result, the high-frequency noise may cause electromagnetic interference to peripheral equipments.