The single electron transistor (SET) fabrication process oil the individual single-walled carbon nanotubes (SWCNTs) using low energy Ar ion irradiation technique has been demonstrated. The individual SWCNT was partly irradiated through the protection resist with the two opening windows, whose width was 50 nm, fabricated by electron beam lithography. The irradiated segments had higher resistance and worked as barriers. The SWCNT SET successfully operated tip to 100 K. (C) 2009 American Vacuum Society. [DOI: 10.1116/1.3002388]