To inexpensively and extremely stably produce a grain oriented silicon steel sheet low in core loss by forming tension-coating of ceramic on the surface of an extremely thin grain oriented silicon steel sheet by the method other than vacuum treating methods such as CVD, ion plating, ion implantation or the like.

On the surface of a smoothened extremely thin silicon steel sheet having 0.01 to 0.15mm thickness, (1) tension-coating of one or ≥ two kinds selected from various oxides, nitrides and carbides shall be formed by using a plasma spraying method. (2) On the surface of an extremely thin silicon steel sheet applied with 0.05 to 5MPa tension, these coating shall be formed. The treatment (1) to (2) shall be executed in the air or in a nonoxidizing atmosphere.