Abstract: The corrosion-preventing additive for reinforced concrete is a concrete additive for preventing corrosion of steel rebars in steel-reinforced concrete. The corrosion-preventing additive is a solution with an organic solvent, the solute being either gallic acid (3,4,5-trihydroxybenzoic acid), at least one ester of gallic acid, or combinations thereof. The weight-to-volume concentration of the solute to the organic solvent may be between 1% and 10% w/v. Reinforced concrete may be made using the corrosion-preventing additive by mixing the corrosion-preventing additive with a conventional concrete mixture (i.e., a mixture of an aggregate, water, and cement), with at least one steel rebar being embedded in the mixture, similar to conventional steel rebar reinforced concrete. The concentration of the corrosion-preventing additive with respect to the cement of the mixture may be between 0.0125 wt % and 1.0 wt %.