Recently, soft magnetic alloys are used for many kinds of applications such as power electrical equipments and electronic appliances. Several ten years ago, only polycrystalline soft magnetic alloys were used for industrial usage. However, around 30 years ago, amorphous soft magnetic alloys produced by the rapid quenching technique were invented and have been developed. Around 15 years ago, nano-crystalline soft magnetic alloys were invented by the authors. This paper reports Fe-Si-Al alloys for the magnetic recording heads, Co-based amorphous alloys for switched mode power supplies, and nano-crystalline soft magnetic alloys with particular emphasis.