PURPOSE: To form an insulated film good in slidability as well as powdering resistance by forming a specified amt. of wax film having a specified m.p. on the surface layer of a silicon steel sheet.

CONSTITUTION: A grain oriented silicon steel sheet is subjected to finish annealing to form an insulated tensile strength coat. Then, on the surface layer, a wax film having ≥80°C m.p. is formed by 0.6 to 2.0g/m2. For uniformly coating it, the method for immersing wax into a duster made of cloth and rubbing it is preferably used. In this way, the objective grain oriented silicon steel sheet free from the deterioration in film properties such as the impartation of tensile strength can be provided.