PURPOSE: To obtain high permeability alloy dust core excellent in high frequency characteristic, by using Fe-Si based alloy powder manufactured by water atomization method which powder has a specified average grain diameter and composition.

CONSTITUTION: Alloy powder manufactured by water atomization method has an average grain diameter of 10-100μm. The powder contains Si of 2-12wt.% and oxygen of 0.05-0.95wt.%, and the residual part is essentially composed of Fe. Al, Cr and Ti are contained by 3% or below in a single state or a compound state. Insulative bonding material is added to the above alloy powder, and then curing process is performed. Thereby a stable oxide film is formed on the alloy powder surface, and high permeability dust core excellent in high frequency characteristics can be obtained.