PROBLEM TO BE SOLVED: To provide a corrosion testing method of a metallic material capable of performing a corrosion test of the metallic material while the generation process of corrosive gas is set in a situation same as the actual environment.SOLUTION: A metallic material is corroded by bringing the metallic material into contact with corrosive gas generated by decomposing a causal material M for generating the corrosive gas. The causal material M is disposed in an internal space S surrounded by the metallic material. The passage connecting the internal space S to the external space can be formed of a clearance c formed by fitting a metal surface to a metal surface. In this case, the fitted surface between the metals can be corroded by circulating the corrosive gas generated by decomposing the causal material M from the internal space S to the clearance c.
