To improve the function of a revetment by forming wire netting to shape a mat-like form and laying the cage-shaped revetment mat on a slope face of the revetment of a river and forming projections on the surface of the mat and further provide a function for a fish nest.

One or more projections 12 are formed on the upper face of a mat member formed to shape a futon (bedding) by wire netting made of steel wires to constitute a cage-shaped revetment mat 11. The projection 12 is a block or the like of a small cage mat, or a block made of porous concrete or ordinary concrete and it is shaped to have an appropriate form and size. A fish nest block is fitted to the mat 11 when required. The fish nest block is shaped with porous concrete to have a frame-form or wooden members are assembled with bolts or strings to have a frame-form. In this way, as the roughness of the revetment is increased by the projections of the surface, a groin effect is brought out to attenuate the water strem and hence, an effective inhabiting space for fish can be formed.