The tank for storing gas at high pressure, such as a tank for a vehicle running on gas, comprises a confinement volume accessible via coupling means and defined by a duct disposed in a spiral coil so that the substantially rectilinear main portions of the duct bear against one another. The forces exerted by the pressure of the gas on the main portions of a turn of the duct are then compensated by the forces exerted on the adjacent turns of the duct.