In the gas shortage detection device of a piston-type hydropneumatic accumulator, a control rod slidably mounted in the cylinder head on the gas side is displaced under the action of the thrust exerted by the piston when this latter comes closer to the cylinder head than a predetermined distance. A flexible motion-reversal coupling element such as an inextensible cord which works in traction and has a predetermined dead range of travel is placed between the piston and the sliding rod. Correct performance of the detection device can thus be checked by partial draining of the oil compartment, the detection device being triggered into operation when the piston comes close to the bottom end of the cylinder.