To obtain a trivalent chromate plating system which is good in corrosion resistance and does not exert advance influence on a human body and environment by minimizing the elution of hexavalent chromium.

The trivalent chromate plating system comprises: making the surfaces of metallic components undergoing galvanizing alkaline active; activating the surfaces of the galvanized films in a treating solution of a nitric acid activation treatment process 12; rinsing the components with water to remove nitric acid components; generating films in a solution of a trivalent chromate treatment process 12 and again rinsing the components; and immersing the metallic components formed with the films into a reduction treatment solution of a prescribed concentration in a hexavalent chromium reduction treatment process 30 thereby reducing the amount of elution of the hexavalent chromium, the amount of elution of the hexavalent chromium is therefore reduced to ≤1/3 as compared with the metallic components not subjected to the reduction treatment and the practicability is promoted as the trivalent chromate film treatment. Also, when the surfaces of the metallic components are subjected to the trivalent chromate film treatment, the elution of the hexavalent chromium can be minimized.