Without using a halogen gas provides a substrate processing method which can increase the etch rate of the copper member. In the substrate processing apparatus 10, having a smooth surface 50 was used to obtain a Cu layer 40, and introduces the process gas was added to the methane gas to hydrogen gas in the inner space of the treatment chamber 15, the process to generate a plasma from the gas and the presence of oxygen radicals (52), and carbon radical (53) resulting from the methane generated during the etching of the oxide layer 42 to the inner space of the processing chamber (15), oxygen radical 52 or the carbon radical generating an organic acid from 53, to produce a complex of an organic acid including the organic acid to the copper atom is reacted with copper atoms of the Cu layer 40, and further evaporation of the resulting complexes.