PURPOSE:To improve impedance and the frequency characteristics of a parallel resistance value by specifying the contents of iron oxide, zinc oxide and manganese oxide and having specific quantities of magnesium oxide and aluminum oxide contained. CONSTITUTION:The composition (X, Y, Z) of iron oxide, zinc oxide and manganese oxide is kept within a composition range surrounded by A(50, 8, 14, 35, 2), B(50, 8, 25, 24, 2), C(46, 27, 27) and D(46, 14, 40) in a three-element composition diagram, and contains only magnesium oxide or magnesium oxide and aluminum oxide. When MgO and Al2O3 or compounds changed into these MgO and Al2O3 through baking are compounded and added, these quantities extend over 2500-14000ppm in total, preferably, 6300-11000ppm. Al2O3 is contained in addition to MgO, thus particularly improving impedance of 10-100MHz, then effectively reducing noises of 100MHz or more.
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