A MnZn ferrite having excellent characteristics of an incremental permeability μΔ value of 250 or greater in a wide temperature range of 0 to 85° C. and an incremental permeability μΔ value of 400 or greater at 65° C. when an 80 A/m direct current magnetic field is applied is provided. The MnZn ferrite has basic components that comprise: ferric oxide (in terms of Fe2O3): 51.0 to 54.5 mol %, zinc oxide (in terms of ZnO): 8.0 to 12.0 mol %, and manganese oxide (in terms of MnO): the balance, sub components that comprise: silicon oxide (in terms of SiO2): 50 to 400 mass ppm, and calcium oxide (in terms of CaO): 50 to 400 mass ppm, and unavoidable impurities phosphorous, boron, sulfur and chlorine that are restricted to phosphorous: less than 3 mass ppm, boron: less than 3 mass ppm, sulfur: less than 5 mass ppm, and chlorine: less than 10 mass ppm.