Provided is a noise reduction device including: a conductive bar of conductive material; a metal tubular portion with a through hole having the conductive bar penetrating therethrough and accommodating a magnetic material core and a substrate therein; a capacitor mounted on the substrate and having a first terminal connected to the conductive bar and a second terminal connected to an inner wall of the through hole; and a blocking unit blocking an opening of the through hole so as to affix the conductive bar with respect to the metal housing and the tubular portion. The tubular portion includes an outer peripheral surface having a threaded engagement part threadedly engaged with the metal housing; and the conductive bar has an outer end that functions as an output terminal.