Cup/valve assembly for an aerosol container, made up of a cup, a valve body, a stem, a spring, an inner seal and means for retaining the stem in the valve body, the cup having at its center an opening through which the stem protrudes, the stem comprising a bulge on its outer cylindrical face and an inner conduit having an upper opening at its upper end and at least one lateral orifice at its lower end, the lateral orifice or orifices being placed between the bulge and the upper opening of the inner conduit, the valve body having a cylindrical portion provided with an opening at its upper end defining a top edge, - wherein the valve body is fixed to the opening of the cup by fixing means, leaving the opening of the cylindrical portion free, - wherein the portion of the stem that extends from the bulge to the end opposite the inner conduit is located inside the valve body, bearing against the spring, - wherein the means for retaining the stem in the valve body are constituted by a retaining ring that surrounds, without tightening, the portion of the stem located between the lateral orifice or orifices and the upper opening of the conduit, the outer diameter of the retaining ring being greater than the diameter of the opening and the inner diameter of the retaining ring being smaller than the diameter of the bulge of the stem, the retaining ring being fixed to the cup by fixing means, the inner seal being interposed between the retaining ring and the top edge of the cylindrical portion of the valve body so that, in the closed position of the valve, the inner seal fits tightly around the stem in the area of the lateral orifice or orifices and obstructs them, and the spring pushes the stem back and places its bulge bearing against the seal. characterized in that - centering means are provided to facilitate the centering of the retaining ring relative to the cup, and in that - the centering means are constituted by a crown placed on the face of the retaining ring oriented toward the cup, this crown being dimensioned to penetrate into a recess located in the cup and surrounding the opening, preferably into a groove formed in the bottom of the recess, wherein the recess can widen in the direction of the retaining ring, at least in its upper portion, and/or the ring can narrow in the direction of the cup, at least in its lower portion, wherein an extra thickness of material can be provided on the crown of the retaining ring or in the groove of the cup to serve as a weld seam. - wherein the valve body is fixed to the opening of the cup by fixing means, leaving the opening of the cylindrical portion free, - wherein the portion of the stem that extends from the bulge to the end opposite the inner conduit is located inside the valve body, bearing against the spring, - wherein the means for retaining the stem in the valve body are constituted by a retaining ring that surrounds, without tightening, the portion of the stem located between the lateral orifice or orifices and the upper opening of the conduit, the outer diameter of the retaining ring being greater than the diameter of the opening and the inner diameter of the retaining ring being smaller than the diameter of the bulge of the stem, the retaining ring being fixed to the cup by fixing means, the inner seal being interposed between the retaining ring and the top edge of the cylindrical portion of the valve body so that, in the closed position of the valve, the inner seal fits tightly around the stem in the area of the lateral orifice or orifices and obstructs them, and the spring pushes the stem back and places its bulge bearing against the seal. characterized in that - centering means are provided to facilitate the centering of the retaining ring relative to the cup, and in that - the centering means are constituted by a crown placed on the face of the retaining ring oriented toward the cup, this crown being dimensioned to penetrate into a recess located in the cup and surrounding the opening, preferably into a groove formed in the bottom of the recess, wherein the recess can widen in the direction of the retaining ring, at least in its upper portion, and/or the ring can narrow in the direction of the cup, at least in its lower portion, wherein an extra thickness of material can be provided on the crown of the retaining ring or in the groove of the cup to serve as a weld seam.