<p>It is possible to realize a common mode chalk coil capable of easily realizing impedance value adjustment by changing the thickness of an impedance value adjusting insulation layer. On the entire main surface of a first magnetic substrate (1), an impedance value adjusting insulation layer (2) is formed. Furthermore, on this layer, a coil pattern and an insulation layer are alternately formed. One or both of insulation layer portion of the center area of each insulation layer surrounded by the coil pattern excluding the impedance value adjusting insulation layer (2) and the coil pattern outer circumference area are removed. Resin containing magnetic powder is provided in the insulation layer (10) of the uppermost layer and the portion where the insulation layer has been removed. A second magnetic substrate (13) is attached via an adhesion layer (12).</p>
