ZnO nanowires were synthesized by the CVD procedure and have been investigated by SEM, TEM, SAED, Raman, and cw PL spectroscopy. The fabrication of an ultraviolet (UV) photoconductive detector based on single ZnO nanowire (100 nm in diameter) is presented. This nanostructure detector is prepared in an Focused Ion Beam (FIB) set-up by using nanodeposition for metal electrodes. The photoresponse of the UV sensor are studied using a UV source with an incident peak wavelength of 365 nm. It was demonstrated that the output signal of the sensors is reproducible under UV irradiation. The photoresponse and characteristics of the ZnO nanowire-device demonstrates that focused ion beam process offers a way to fabricate novel nanodevices on a single ZnO nanowire with diameters as small as 100 nm. The presented single ZnO nanowire sensor proves to be promising for application in various processes.