To economically manufacture a weir in an easy manufacturing process and improve strength and durability by including at least two layers of reinforcing fabrics as rubber sheets for forming rubber bag-shaped bodies and providing an intermediate rubber layer having a specified thickness and hardness between the reinforcing fabric layers.

A rubber sheet S forming a rubber-made bag-shaped body in a rubber- made weir is constituted of a reinforcing layer R in which a rubber layer 5 is disposed in between at least two layers of reinforcing fabrics 4, 4, an upper cover rubber 3 arranged at the external direction of the bag of one layer of reinforcing fabric 4 of the reinforcing layer R, and a lower rubber cover layer 6 arranged at the internal direction of the bag of the other reinforcing fabric 4. The thickness of the intermediate rubber layer 5 is made not less than 1 mm to secure an impulse-resistant function and the hardness thereof is made to range from 35 to 65 to improve the balance of various material properties such as strength, flexibility, etc. The rubber sheet S can be economically manufactured in an easy manufacturing process, and the rubber sheet is provided with a certain strength and durability and can sufficiently withstand a severe natural environment, a high water pressure, and impulses caused by driftwood or boulder stones.