PURPOSE: To improve durability of a film by coating an ink jet orifice surface with resin composition in which inorganic or organic fine particles are filled in amorphous thermoplastic resin having a perfluoro structure, and adding filler in liquid repellency agent.

CONSTITUTION: An ink jet orifice surface is coated with resin composition in which inorganic or organic fine particles are filled in amorphous thermoplastic resin having perfluoro structure. As the polymer compound having the perfluoro structure, amorphous thermoplastic resin having a perfluoroheterocycle structure is used. As the inorganic filler to be filled therein, titanium oxide, aluminum oxide, etc., is used, and as the organic filler, polyacrylamide, etc., is used. Then, a surface treating method adds to disperse perfluoro compound soluble in specific solvent or fluorine-containing compound insoluble in solvent in perfluoro compound soluble in general organic solvent thereby to improve its mechanical strength without reducing water repellency continuity.