Abstract: Device for inflating balloons, particularly balloons supported by tubular shafts, comprising a one-way valve mounted in or at one end of the shaft to be inserted into the neck of the balloon. The valve is provided externally with a projection and rings to deform the neck of the balloon elastically, and ensure the retention of the inflation pressure of the balloon. This sealing may be improved by a tapered sleeve. The valve is made of two parts joined together and forming a cylindrical cavity enclosed by two bases, of which one is smooth surfaced with a central axial hole and the other one is provided with radial ribs and a central axial hole opening into the balloon. A sealing element which may be a thin sheet, a sphere or a hollow piston with tapered element, slides freely in the cylindrical cavity. The valve can also be of a type manually inserted and placed at one end of the supporting shaft.