To attenuate noise having a frequency component of the order of several GHz by setting the product of the electrical conductivity and magnetic permeability of a conductive member, having a first material and a second material larger than the product of the electrical conductivity and magnetic permeability of a conductive member which has either of the first or second materials and not have the other material.

When the skin depth of a conductive member to which current is concentrated by the skin effect is defined as δ, it can be expressed as #={2/(ωσμ)}1/2, (ω: angle frequency, σ: electric conductivity, μ: magnetic permeability). For example, when a first material is silver, a second material is a ferrite, the product of the conductivity σ and the magnetic permeability μ is σμ2, and that of a conductive member having silver but not ferrite as a comparative conductive member is set as σμ1, the quantity of ferrite to be contained is selected so that σμ2 is larger than σμ1, whereby the skin depth σ can be set smaller than that of the comparasion conductive member. Thus, the skin depth σ of frequency of a noise can be also minimized, and high frequency noise can be attenuated.