PURPOSE: To form a colored chromating film having high Cr content and excellent in corrosion resistance by subjecting the surface of a Zn-Ni alloy-plated steel sheet to electrogalvanizing prior to chromate treatment.

CONSTITUTION: In forming the chromating film on the surface of the steel sheet plated with Zn-Ni alloy containing ≤20wt% Ni, an electrogalvanizing layer of ≤1μm thickness is formed as pretreatment on the Zn-Ni plating film. Subsequently, a high-Cr-content chromating solution having a Cr6+ concentration of 0.5W100g/l, a weight ratio between SO42- and Cr6+ concentrations of 0.025W1.5 and a pH value of 1.3W2.7 is applied, so that the colored chromating film having high Cr adhesion quantity and excellent in corrosion resistance can be formed.