An apparatus for removing attachments deposited on a surface of an underwater structure and preventing that such attachments be deposited thereafter. The apparatus is floated on the water surface or underwater and with the aid of a natural force repeatedly impinges upon the surface of the structure to remove attachments deposited thereon. The apparatus has a first rope being provided around the surface of the structure at the water surface level, and at least one or more rotating members threaded with said first rope and being freely rotatable about the rope. The rotating members impinge upon the surface of the structure when the apparatus floats on the water surface level or underwater shaving off attachments deposited on the structure, and preventing any further attachments from being deposited thereafter. It is preferred to provide some protruding portions on the surface area of the rotating members where the rotating members impinge upon the surface of the structure.