A zinc-rich water-based paint blends a binder and a chelating agent in a zinc slurry. The zinc slurry is blended in an amount of 61.7% by weigh. A potassium as the binder is blended in an amount of 30.0% by weight. A blending quantity of an ion exchange water is decreased as a blending quantity of EDTA-4K as the chelating agent is increased such as 0.2, 0.4, 0.7, 1.4 and 2.4% by weigh as, so that a total quantity becomes 100%.