An ink jet head includes a nozzle plate substrate having a nozzle for ejecting ink toward a recording medium and an oil repellent film on a surface of the nozzle plate substrate, the surface facing the recording medium. The oil repellent film comprises a fluorine compound having a first end and a second end, the first end comprising a perfluoroalkyl group with 3 to 5 carbon atoms per each molecule of the fluorine compound, and a ratio of a density of CF2 groups in the oil repellent film with respect to a density of CF3 groups in the oil repellent film is between 1.5 and 4.0 as measured by X-ray photoelectron spectroscopic analysis.