A producing method for an electrical insulating structure that covers an outer surface of a to-be-insulated object is provided. The method comprises: a taping step of winding a main insulation tape on outside of the to-be-insulated object; a spraying step of spraying nanoparticles onto the outer surface of the wound main insulation tape; a vacuum drawing step of vacuum drawing the tape-wound to-be-insulated object; and an impregnation step of injecting a nanoparticle-containing impregnating macromolecular polymer in which nanoparticles have been kneaded to impregnate the to-be-insulated object therewith. In the spraying step, microcapsules, which contain the nanoparticles and are able to release the nanoparticles before the impregnation step, are sprayed.