PURPOSE: To prevent DC magnetic deflection without lowering magnetic flux density by utilizing an amorphous magnetic foil material having a high excitation capacity as an iron core.

CONSTITUTION: An iron core of a static induction device such as a transformer which receives a DC field stress is formed with an amrophous magnetic material. It is designed so that it has the excitation capacity of 20W50 times as compared with that of conventional directional silicon steel belt and thereby satruation of iron core by field stress can be prevented. From the point of view of magnetic field circuit, large excition capacity is equivalent to the existence of air gap. Accordingly, a DC magnetic deflection can be prevented without lowering magnetic flux density.