A nanometer-scale recording technique was demonstrated on N-(3-nitrobenzylidene) p-phenylenediamine (NBPDA) organic thin films with a scanning tunneling microscope (STM). NBPDA thin films were fabricated by vacuum thermal deposition. The results of ultraviolet-visible absorption and infrared transmission spectra showed that the structure of the NBPDA film was the same as that of NBPDA crystal. An atomic force microscope was utilized to characterize the surface morphology of the NBPDA film. Data were recorded by applying voltage pulses between the tip and the substrate. The current-voltage characteristics measured by the STM indicated that the local electrical property changed from an insulating property into a metallic property after the data were written. Data marks, 1.4 nm in diameter, corresponded to a data storage density of 10(12) bits/cm(2). A preliminary calculation was presented to explain the recording mechanism.