A Mn—Zn based ferrite having a main component comprised of 51 to 54 mol % of an iron oxide in Fe₂O₃ conversion, 14 to 21 mol % of a zinc oxide in ZnO conversion and the rest of a manganese oxide, wherein a content ( [ppm]) of cobalt oxide in a CoO conversion with respect to 100 wt % of the main component satisfies a relation formula below.

Note that Y1 and Y2 are expressed by the formulas below and CoO0 [ppm].

The A and B in the above Y1 and Y2 are A=Fe₂O₃ (mol %) and B=ZnO (mol %).