The present study generated an extremely high vacuum of 10−10 Pa by very common methods such as using SUS304 chamber material, electropolishing surface treatment and turbomolecular pumping technology. We examined the gas phase and electron-stimulated desorption ions of the ion gauges, the effect of ambient temperature, total pressure and H2 partial pressure. One of the results showed that, as is well known, most of the residual gas in the extremely high vacuum chamber was H2 but there was also a little F, which is not so well known.