The present invention provides: a chemical agent composition capable of inhibiting, in a wood treatment device for impregnating wood with the chemical agent composition, corrosion of iron components or the like which may come into contact therewith and a method for inhibiting corrosion of said iron components or the like. In one or more of the embodiments of the present invention, an iron-corrosion inhibition method for a wood treatment device includes a step in which the wood treatment device is used to impregnate wood with a chemical agent composition. The treatment device is provided with iron components or parts which come into contact with the chemical agent composition. The chemical agent composition is an aqueous solution composition including an iodopropynyl carbamate compound and a quaternary ammonium organic salt.
