PURPOSE: To obtain an agent for safely and easily suppressing the growth of polymer in the titled apparatus, by using at least one kind of compound selected from hydroxylamines, oximes, mercaptans, alkanolamines and diamines as a main component.

CONSTITUTION: The objective agent for suppressing the growth of polymer is produced by using at least one kind of compound selected from hydroxylamines, oximes, mercaptans, alkanolamines and diamines as a main component. The component is preferably used in combination with one or more kinds of additives selected from polymerization inhibitor, antioxidant and surfactant. The agent is effective in preventing and suppressing the troubles of the adhesion and deposition of polymers on the inner surface of a olefin-production apparatus, especially a fractionation column. The suppressing agent is dissolved in water and/or a water-soluble organic solvent or mineral oil at a concentration of 1W5wt.% and the inside of the apparatus is filled with the solution in the suspension of the operation.