To enable free variation, regulation, and movement in a manner to match with an environmental condition at an individual place by providing a flexible cloth-form substance, mounted between a support weight body arranged on a sea bottom and a floating body in sea, and a weight and coupling the weight and a floating body or the cloth-form body by a mooring rope.

A membrane type training jetty comprises a support weight 1, a cloth-form substance 2, a floating body 3, a mooring rope 4, and a weight 5 and when it is released in sea, a heavy support weight body 1 and the weight 5 are dropped to a seat bottom. In which case, when the mooring rope 4 and the weight 5 are released separately from the weight support body 1 and the floating body 3, after the mooring rope 4 first having a long length is mounted on the floating body 3, winding is effected by a winch until the cloth form substance 2 stands upright, and the other end is re-attached to the weight 5. By opening the cloth-form substance 2 and hanging it down from the floating body 3, an arrangement work is completed. Thus, a shape is formed and adjusted in an optimum state according to an environment condition in an individual place.