OIL-REPELLANT VENTILATION FILTER

A gas-permeable filter provided with oil repellency is provided. The gas-permeable filter includes a porous membrane having a surface coated with an oil-repellent agent. The oil-repellent agent includes a linear fluorine-containing hydrocarbon group represented by -R 1 C 5 F 10 CH 2 C 4 F 9 or -R 2 C 6 F 13 , and the porous membrane is a stretched polytetrafluoroethylene (PTFE) porous membrane. Here, R 1 and R 2 are each independently an alkylene group having 1 to 12 carbon atoms or a phenylene group. The gas-permeable filter is provided with oil repellency without significant reduction in gas permeability.