With the miniaturization of various types of components and devices, micro- and nanometer-scale tools are increasingly in demand. Electrochemical machining (ECM) is a well-established technique for the fabrication of micro tools and nano tips. This paper presents a machining method for the fabrication of a high-aspect-ratio cylindrical nano tool using liquid membrane ECM, in which a straight reciprocating motion is applied to the anodic electrode. The method is based on periodic machining of the anodic rod within the amplitude of the straight reciprocating motion. In this process, the machining rate within amplitude varies periodically, allowing nano tools with high aspect ratios to be obtained by the presented method. Experiments were conducted to verify the proposed method. The influences of applied voltage, electrolyte concentration, amplitude and velocity of the straight reciprocating motion on the fabrication of cylindrical nano-electrode were investigated. By using this method, nano-electrodes with average diameters of several hundred nanometers and aspect ratios up to 70 were successfully fabricated.