The invention provides a radiation-sensitive resin composition, by which a patterned insulation film whose water repellency varies is easily formed with high precision, a process for forming a patterned insulation film using this composition, a display element and an flat-panel disply device using the composition, and a process for producing the flat-panel disply device. The resin composition comprises (A) an alkali-soluble copolymer, (B) a 1,2-quinonediazide compound and (C) a water-repellent siloxane resin in particular proportions. In the production process of the patterned insulation film, patterning exposure and development are conducted on a coating formed of the resin composition. The display element and flat-panel disply device are equipped with an interlayer insulation film formed by the resin composition. The production process of the flat-panel disply device comprises an interlayer insulation film-forming step including a treatment of patterning exposure exposing conductor layer-forming regions in an exposure that only surface layer portions are cured in one part thereof, and the whole in the thickness-wise direction thereof is cured in the other parts, and a conductor layer-forming step of forming conductor layers on the surface of the interlayer insulation film with a liquid material.