To obtain an environment-friendly, permanent and easy method for stabilizing a riverbed by preventing sediment on upstream and midstream sites of a river from flowing down.

Natural stones and rocks under water on upstream and midstream sites of a river and in a river location, or artificial stones and rocks separately manufactured in such a manner as to have their forms imitated from the natural stones are connected together in the state of being each movable in close vicinity to one another, by using a durable material such as metal, and installed under the water and in the river location. Thus, sediment under the stones and the rocks and on the upstream side is pushed and stopped to be prevented from flowing down for stabilization of a riverbed.