A method for measuring a distance of diffusion of a curing catalyst for a thermosetting silicon-containing material includes the steps of: forming a silicon-containing film from a composition containing a thermosetting silicon-containing material, a curing catalyst and a solvent; coating the silicon-containing film with a photosensitive resin composition containing a resin whose solubility in alkaline developer is increased by the action of an acid, an acid generator and a solvent, and subsequently heating to prepare a substrate on which the silicon-containing film and a resin film are formed; irradiating the substrate with a high energy beam or an electron beam to generate an acid and heat-treating the substrate to increase the solubility of the resin in an alkaline developer by the action of the acid in the resin film; dissolving the resin film in an alkaline developer; and measuring a film thickness of the remaining resin.