To obtain a coating giving coating films having small viscous drag to water by compounding a water-soluble polymer in a specific amount based on the total amount of solid contents.

This coating contains a water-soluble polymer (a polymer having a property soluble in water at the ordinary temperature, such as polyethylene oxide, polyacrylamide, hydroxyethylcellulose, carboxymethylcellulose, xanthane gum, etc.), in an amount of 20-100 wt.% based on the total solid amount of the solid contents contained in the coating. When the coating is coated, for example, on the surface of the bottom portion of a ship, a coating film containing the water-soluble polymer in an amount of about 20-100% is formed on the surface of the bottom portion. The coating film containing the water-soluble polymer in the large amount is easily swollen with water and gradually elutes the water-soluble polymer from the surface of the coating film into the water to reduce the viscous drag of the ship to the water.