To solve a problem that a breakwater effect is insufficient because a buoy floating and moored on a race water surface in a motorboat race station, a river, a reservoir, a lake, and sea and having a breakwater function cannot be maintained in a straight line on a water surface.

In this buoy composed of pultiple netlike inner cylinders incorporated in a netlike outer cylinder and having the breakwater function, clamping bolts are fitted into both ends of a hollow pipe provided at the center of the netlike inner cylinder and the clamping bolt and a wire rope having stoppers at required intervals pass through the hollow pipe to fix the buoy by positioning the stoppers at front and rear ends of a semicircular cap of the buoy. A chain of an anchor connected with an eye bolt of a cylindrical clamping body fitted around the buoy through a shackle is crossed and is fixed on the sea bottom to handle the upper end of the chain on the water surface.