To make it possible to rapidly and easily form a water repellent film.

A reactive gas forming section 22 of a reactive gas supply section of a water repellent film forming apparatus 10 forms gaseous fluorine by discharging electricity via the gaseous tetrafluorocarbon and gaseous oxygen introduced therein and supplies this gas to a discharge section. A bubbling device 16 supplies gaseous helium past decane 38 to the discharge section. The discharge section 14 forms active species by discharging the electricity via a gaseous mixture 50 composed of the gaseous helium contg. the decane and the gaseous fluorine under the atm. pressure supplied to the discharge regions 66, 68 between discharge electrode sections 54, 56 and a grounding electrode 62. The active species are supplied to the ink injection surface of a printer head 70 arranged on the grounding electrode 62, by which the water repellent film incorporated with the fluorine into the decane is polymerized.