Electrical steel sheet with insulating coating, method for producing the same, and coating agent for forming insulating coating

An object of the present invention is to provide a magnetic steel sheet with an insulating coating having excellent hardness, suitable as a material for an iron core of a large generator, and a method for producing the same. A coating agent for forming an insulating film characterized in that the solvent contains the following components (A) to (C): (A) Water-based carboxyl group-containing resin: 100 parts by mass in terms of solid content, (B) Aluminum-containing oxide: selected from the group consisting of more than 40 parts by mass and less than 300 parts by mass in terms of solid content, and (C) melamine, isocyanate, and oxazoline with respect to 100 parts by mass in terms of solid content in (A) above. At least one cross-linking agent: 100 parts by mass or more and less than 300 parts by mass in terms of solid content with respect to 100 parts by mass in terms of solid content in (A). [Selection figure] None