To prevent the adhesion of aquatic organisms to a target coated material such as the bottom of a ship, a buoy, a raft, a rock face, a fence for fish culture, etc., at low toxicity without destroying a life cycle of marine organisms, etc., by supporting a basic substance on a coating material convering the surface of the target coated material.

The method for preventing the adhesion of aquatic organism comprises supporting (B) a basic substance such as calcium hydroxide on (A) coating material (e.g. one comprising a binder obtained by blending an inorganic binder such as a cement with an organic binder such as and acrylic resin and a fine aggregate) cover the surface of a target coated material (e.g. one composed of a material such as an iron material, glass, a wood, a reinforced plastic, concrete or a resin) to raise the basically of water acting on the surface of the component A.