PURPOSE: To produce the title substrate for a highly reliable heating element with a smaller number of stages by coating a material capable of forming an insulating layer by heating on the surface of the substrate, projecting a high-density energy flow to heat and melt the material, and forming an insulating layer.

CONSTITUTION: The material such as the powder of metallic Al, etc., capable of forming an insulating layer by heating is coated on the surface of the substrate. A high-density energy flow is projected on the surface of the substrate 8. For example, laser light 2 is introduced to a condensing and oscillating optical system 6 by a mirror 3 from a laser oscillator 1, and projected on the surface of the substrate 8 with specified intensity and spotting by a concave mirror and a scanning mirror 9. As a result, the material is rapidly heated and melted, and a layer having an insulating property is formed on the substrate surface. By this method, a substrate for a heating element having specified surface roughness and capable of being enlarged is obtained.