PURPOSE: To remove the contaminant of grease by coating the surface of an article with a film forming resin contg. a resin previously made water-soluble and a swelling material as the effective component and bringing the article into contact with cleaning water after the article surface is contaminated.

CONSTITUTION: The surface of an article is coated with a film forming resin contg. a resin previously made water-soluble and a swelling material as the effective component, and the article is brought into contact with cleaning water after the article surface is contaminated. The decontaminating agent consists of a film forming resin contg. a resin made water-soluble and a swelling material as the effective component. One or ≥2 kinds among PVA, carboxymethyl cellulose, hydroxypropyl cellulose, methyl-cellulose, polyethylene oxide, etc., are used for the water-soluble resin. A highly water absorptive polymer based on starch, cellulose, synthetic polymer, etc., is exemplified as the swelling material.