PURPOSE: To eliminate the necessity using a fluorocarbon washing solution, to improve the danger of a fire and to accelerate washing by subjecting an article having a contaminate adhered thereto to pressure treatment by together using inert gas and a solvent or water dissolving the contaminate to remove said contaminate.

CONSTITUTION: An article having a contaminate adhered thereto is subjected to pressure treatment by together using inert gas, especially, nitrogen gas and a solvent dissolving the contaminate, for example, isopropanol to remove the contaminate. Therefore, isopropanol has combustibility but the danger of a fire is eliminated by nitrogen gas and the removal of the contaminate is facilitated and the use amount of isopropanol is reduced. When the contaminate is water-soluble, nitrogen and water are together used to pressurize the article and, therefore, the removal of the contaminate is facilitated and the article becomes easy to sufficiently clean. By this method, it is unnecessary to necessarily use a fluorocarbon washing solution being in question and, if used, the use amount of said solution can be markedly reduced.