To obtain a resin compsn. which can be easily produced and shows excellent stability in viscosity and which enables formation of a good image by incorporating a photoacid producing agent, a solvent and a complex prepared from a basic compd. and a polyimide which is soluble with an org. solvent.

This compsn. contains a photoacid producing agent, a solvent and a complex prepared from a basic compd. and a polyimide which is soluble with an org. solvent. This photosensitive resin compsn. is applied by dip coating, spray coating and the like on a substrate such as a silicon wafer and a metal substrate, and properly dried by heating to remove the solvent to form a film having no adhesion property. Then the coating film is irradiated with active rays or chemical rays through a mask having a desired pattern. Since an acid is produced by irradiation, the solubility in the irradiated part increases. Therefore, by dissolving and removing the irradiated part with a developer, a desired positive pattern can be obtd. Thus, the compsn. can be easily produced. has excellent viscosity stability, and enables formation of a good image.