PURPOSE: To prevent deterioration of magnetic characteristics and improve workability of manufacture by a method wherein, when a magnetic distortion of a magnetic thin strip is positive, the end surface of lamination of a core is covered with an insulating inorganic layer with a thermal expansion coefficient smaller than that of the magnetic thin film and, when a magnetic distortion of the magnetic strip is negative, the end surface of lamination of the core is covered with an insulating inorganic layer with a thermal expansion coefficient larger than that of the magnetic thin strip.

CONSTITUTION: A magnetic thin strip 1 is composed of a predominantly amorphous alloy thin strip made by super chilling method or a silicon iron alloy thin strip made by super chilling method or a thin strip made by mechanical method or the like and has a relatively thin strip thickness. The thinner the strip thickness, the thinner the thickness of the insulating inorganic layer 2 and the more effective. When an amorphous alloy of Fe, B, Si system, for instance Fe79, B16, Si5, is used for the magnetic thin film 1, the magnetic distortion of this material is 27×10-6 and its thermal expansion coefficient is approximately 100× 10-7/°C. Therefore, an alumina ceramic with a thermal expansion coefficient 90×10-7/°C is used for the inorganic layer 2 formed on the end surface of the core and the inorganic layer are impregnated with resin as necessary.