PURPOSE: To obtain with good productivity the titled sheet good in workability, by applying a specified resin varnish to glass fiber or the like, putting the glass fiber on a film, winding them on a core metal under pressure, removing the film, putting the glass fiber on a heat resistant porous sheet, and winding them on a core metal, setting the resins and removing the film.

CONSTITUTION: A (non)woven strip-like heat resistant base 1 consisting of one or more glass fiber, asbesto fiber, carbon fiber and potassium titanate fiber is coated and impregnated with the polyamide-imide resin varnish 2, then the base 1 is heated in a hot air drying oven 4 to up to a temperature at which the solvent in the varnish boils to obtain a resin treated base 6 in the state of dry to touch, the base 6 and a polyester film 7 are put together, then while they are under tension respectively they are heated to up to a temperature at which the solvent boils, and they are wound around the core metal 10 under pressure by a press roller 12 to obtain a primary molded item 11. Then after the polyester film is released, the molded item and the air-permeable heat-resistant porous sheet 13 are put together and are wound around the metal core 14, the wound item is heated gradually to or above a temperature at which the solvent boils to set the resin, and then the porous sheet is removed to obtain the intended sheet.