The soft magnetic thin film has high saturation magnetic flux density and good soft magnetic characteristics. The soft magnetic thin film of the present invention is formed by electrolytic plating. The plated film is made of FeCo, whose composition is indicated as FexCo1-x (60.ltoreq.x.ltoreq.75 wt %), the FeCo film has a bcc crystal structure, and the crystal of the FeCo film is oriented to a crystal face of (110).