To provide a method for producing a chromate treated galvanized steel sheet excellent in hardness to dissolve in which Zn in a plating film and Cr6+ in a chromate treating soln. are securely reacted to increase the ratio of Cr3+ in the film and to provide equipment therefor.

This is the method for producing a chromate treated gaivanized steel sheet in which a galvanized steel sheet is coated with a coating type chromate treating soln., and after that, at least till the completion of the reaction of Zn in the above plating and Cr6+ in the above chromate treating soln., the relative humidity of the atmosphere to be contacted with the galvanized steel sheet is regulated to 50 to 98%RH. Thus, the drying of the chromate treating soln. is prevented to facilitate the reaction between Zn and Cr6+.