We report on the preparation and electrical characterization of nylon-6 nanofibers via electrospinning technique. During electrospinning, the polymer solution became highly ionized and emerging out of the micro-tip syringe by forming mesh-like ultrafine nanofibers structure in between the main fibers. The resultant nylon-6 nanofibers were well-oriented with uniform structure. The diameter of the ultrafine nanofibers (7 to 40 nm) is one order less than those of main fibers (100 to 200 nm). The current-voltage (I-V) measurements revealed a linear curve with an occurrence of negative differential resistance (NDR) behavior. The existence of NDR region in the nylon-6 nanofibers can be attributed to the tunneling current through the ultrafine structures. The fabrication of nanofibers, in the form of ultrafine mesh-like form, is relatively fast and inexpensive, and it paves the way to build up of new dimension for nano device applications.