Native oxide film on a semiconductor silicon wafer(s) is dry etched at a temperature of 50° C. or less. Hydrogen treatment is then carried out a temperature of 100° C. or more to bond the dangling bonds with hydrogen. A jig 9 that has been used is again used for loading new semiconductor silicon wafer(s) 10. The wafer(s) on the jig 9 is subjected to removal of a native oxide film and then hydrogen bonding. The resultant heat remains in jig and makes it difficult to maintain the wafers to temperature appropriate to removal of a native oxide film.After treatment of hydrogen bonding, inert gas having temperature of from 0 to −30° C. is injected into reaction vessel 5 and/or treatment preparing vessel 21, in which a native oxide film has been removed.