PURPOSE: To enable a testing condition for sending gas at a constant concn. in a constant amount and further controlling a temp. and humidity constantly, by constituting the titled apparatus from a means for supplying corrosive gas into a chamber receiving a test piece, a means for supplying steam into the chamber and means for applying load to the test piece.

CONSTITUTION: A test piece 10 is received in a chamber 5 through a shaft seal 11 and gas is supplied into said chamber. A means for adjusting the concn. and the flow amount of the gas consists of a bomb 1 for storing reference gas containing H2S in a predetermined concn., a valve 2 provided to the outlet of the bomb 1 and controlling the gas flow amount of a primary side, a quantitative pump 3, a dilution chamber 13 for diluting the gas branched from the quantitative pump 13 and a pump 4 for emitting the diluted gas. By this mechanism, gas concn. and the gas flow amount are automatically controlled and the gas can be supplied to the chamber 5. A means for supplying steam into the chamber 5 consists of a humidifier 6 for storing heated water and the heater 8 received therein. The heater 8 is controlled by psychrometric controller (not shown in the drawing).