To provide a method for producing an aquatic creature antifouling resin composition to be used for inhibiting adhesion of aquatic creatures to an underwater structure, a fishing implement, a ship bottom, a waterway, a cooling pipeline, an ocean civil engineering-related materials such as a silt fence, a cooling tower or the like.

The method for producing the aquatic creature antifouling resin composition comprises swelling at least one kind of a resin selected from the group consisting of a polyurethane resin, a polyurea resin and a polyurethane-polyurea resin with an organic solvent containing a chemical. This aquatic creature antifouling resin composition is satisfactorily simple and inexpensive, facilitates control of the carrying amount for effective ingredients, enables development of effects for long period of time, and can use available various chemicals of which effectiveness is known as effective ingredients.