To provide a method for controlling fouling of an alkali scrubber.

This method comprises controlling the formation of fouling deposit produced on the surface of an alkali scrubber useful for cleaning of an acidic gas prepared during the production of an olefin. The deposit is produced during the scrubbing of hydrocarbons prepared by an alkali solution having pH >7. In this method, an alkali solution of a substituted aromatic amine soluble in the alkali solution, selected from the group consisting of 2- aminophenol, 4-aminophenol, 4-amilnobenesulfonate, its salt, 4-amino-o-cresol, 3-aminophenol, 2-aminobenzoic acid and its salt, 3-aminobenzoic acid and its salt, and 4-aminobenzoic acid and its salt in an effective amount to control the deposit is added to the alkali solution.