PURPOSE: To improve corrosion resistance after stress relief annealing to a greater extent by suppressing the halogen element and alkali metal in a treating liquid at the time of forming a chromium compd.-org. resin base insulating film on the surface of an electrical steel sheet.

CONSTITUTION: The treating liquid contg. ≤10ppm halogen element and ≤40ppm alkali metal is coated on the surface of the electrical steel sheet and is baked to form the insulating film at the time of forming the chromium compd.-org. resin base insulating film on the surface of said sheet. A compsn. consisting of; for example, 130pts.wt. aq. soln. of 30% magnesium dihromate, 25pts.wt. acrylic/vinyl acetate resin emulsion (40% resin solid content), 7pts.wt. etylene glycol and 10pts.wt. boric acid is used as the treating liquid of this time. As a result, the corrosion resistance after strews relief annealing is improved to a greater extent.