Abstract: A floating roof of a tank for storing liquids consisting of a resilient disc-shaped diaphragm attached, leakproof fashion, all the way around its circumference to an annular seal and further attached to a floating chamber at the center which is fitted to an upright with provision for displacing along same when the level of liquid is changing. The resilient disc-shaped diaphragm is made hollow and is corrugated in the radial and circumferential directions so that the corrugations form a plurality of cells. The diaphragm rests on a series of radially disposed telescopic arms each attached with one of its ends to the floating chamber and resiliently connected at its free end to the annular seal. A rool of this type can practically be used with tanks of any shape.