To provide a plasma corrosion method capable of improving an effect of the plasma corrosion.

A substrate has at least one resin layer 10 and at least one copper layer 20 for covering a surface of the resin layer 10. The copper layer 20 has an exposed surface and an opening 21 for penetrating through from its surface to the resin layer 10. The plasma corrosion method comprises the steps of forming an oxide layer mask 40 on the surface by contacting the copper layer 20 to a chemical, removing the resin material facing to the opening 21 with the plasma corrosion method using gas including oxygen. To form the oxygen layer mask 40 on the surface of the copper layer 20, the two copper layers 20 prevent the reaction with oxygen free radical to improve the effect of the plasma corrosion without decreasing a density of the oxygen free radical (O).