A noise reducer is provided that ameliorates electromagnetic noise interference. More specifically, the noise reducer ameliorates electromagnetic noise interference for electronic equipment caused by noise superimposed on a conductor wire. The conductor wire includes a magnetic cylindrical core that penetrates a hollow hole, a winding coiled around the magnetic cylindrical core, and an impedance element connected to the winding. When a noise current is superimposed on the conductor wire that has been made to penetrate the magnetic cylindrical core, part of the noise current is electromagnetically induced from the conductor wire to the winding and flows to the winding. The noise current that flows to the winding is transformed into heat and consumed by the impedance element. As a result, the noise power that gives electromagnetic noise interference to the electronic devices can be reduced and the electromagnetic noise interference for the electronic devices ameliorated.