A post-etch treatment method capable of imparting high corrosion prevention performance to the aluminum-containing wiring films. The sample of aluminum-containing wiring material that is etched using the halogen-type gas is treated with the plasma of a gas that has the oxygen component, and the resist formed on the aluminum-containing wiring material is reacted with oxygen and is removed. Further, the plasma is generated using a gas having the hydrogen component or this gas is liquefied into droplets thereof on the sample surface, so that halogen components (Cl, Br, etc.) adhered to the aluminum-containing wiring material through the etching treatment are reacted with hydrogen and are effectively removed in the form of hydrogen chloride (HCl) or hydrogen bromide (HBr). This makes it possible to obtain the aluminum-containing wiring material having high corrosion prevention performance.