A semiconductor device production method that is used to uniformly and efficiently reduce metal oxides produced on metal (copper, for example) which forms electrodes or wirings on a semiconductor device. An object to be treated on which copper oxides are produced is put into a process chamber and is heated by a heater to a predetermined temperature. Then carboxylic acid stored in a storage tank is vaporized by a carburetor. The vaporized carboxylic acid, together with carrier gas, is introduced into the process chamber via a treating gas feed pipe to reduce the copper oxides produced on the object to be treated to metal copper. As a result, metal oxides can be reduced uniformly without making the surfaces of electrodes or wirings irregular. Moreover, in this case, carbon dioxide and water are both produced in a gaseous state. This prevents impurities from remaining on the surface of copper.