A 30 kV fine focused ion beam machining system was constructed in which a Ga ion beam extracted from a needle‐type liquid metal source is focused into a submicron spot by a three‐electrode electrostatic lens and deflected by an octapole deflector. Vacuum rate at the work stage is 10−7–10−8Torr. With blanking electrodes, the machined area can be confined to any rectangular area determined by the cursol lines on the scanning ion microscopic display. Probe current is higher than 0.3 nA for a 0.3 μm diam spot and current density is over 0.71 A/cm2. At a scanning speed of 100 μm/s, grooves 0.2 μm wide are made in a gold film 0.1 μm thick. By scanning repeatedly, a groove is produced in a (100)Si wafer yielding a cross section having a very sharp V shape with an aspect ratio of 8:1. Two‐dimensional scanning removal is performed under various conditions at the same dose of 1.9×1018ion/cm2, resulting in very different hole shapes. Removal at a scanning speed of 1 mm/s with 200 repetitions produces a uniform shallow hole shape, while removal at 5 μm/s with one repetition results in an inclined deep hole shape. Observation of the cross section shows that this inclined area protrudes from the side wall of the hole, formed through the redeposition of sputtered silicon. These results show the importance of the redeposition process in removal utilizing fine focused ion beams. Also, the differing results of two scanning methods appear to demonstrate the nonlinear sputter effect in fine focused ion beam machining.