System for aiding in the replacement of a mold intended to be used for the replacement of at least one mold of a molding unit equipping a machine for manufacturing containers by the forming, by means of at least one fluid under pressure, of a preform made from a plastic material having been thermally conditioned beforehand, said molding unit comprising at least: - two mold carriers which are mounted so as to be movable between at least one open position and one closed position of the molding unit, and - a mold comprising at least two molding elements capable of being brought together in order to occupy a joined position, or of being separated in order to occupy a disjoined position, in which the said system for aiding comprises at least one device for transporting a mold forming a transportable unit subassembly, known as a joined mold, the said transport device comprising at least one robotic arm for positioning, in space, with respect to the molding unit, means for handling at least one joined mold so as to carry out a replacement of the said at least one mold of the said molding unit, characterized in that each of the said at least two molding elements of the mold is adapted to be secured in a detachable manner to one of the associated mold carriers by associated securing means, the said associated securing means are adapted to be controlled when the molding unit is in the closed position between at least one securing position and one release position, in that the said handling means comprise at least one principal holding device intended to interact with a first part of the joined mold which is accessible to the said principal holding device when the molding unit is in the closed position, and in that the said robotic arm is designed for positioning, in space, the said handling means with respect to the molding unit along a trihedron (X, Y, Z). - two mold carriers which are mounted so as to be movable between at least one open position and one closed position of the molding unit, and - a mold comprising at least two molding elements capable of being brought together in order to occupy a joined position, or of being separated in order to occupy a disjoined position, in which the said system for aiding comprises at least one device for transporting a mold forming a transportable unit subassembly, known as a joined mold, the said transport device comprising at least one robotic arm for positioning, in space, with respect to the molding unit, means for handling at least one joined mold so as to carry out a replacement of the said at least one mold of the said molding unit, characterized in that each of the said at least two molding elements of the mold is adapted to be secured in a detachable manner to one of the associated mold carriers by associated securing means, the said associated securing means are adapted to be controlled when the molding unit is in the closed position between at least one securing position and one release position, in that the said handling means comprise at least one principal holding device intended to interact with a first part of the joined mold which is accessible to the said principal holding device when the molding unit is in the closed position, and in that the said robotic arm is designed for positioning, in space, the said handling means with respect to the molding unit along a trihedron (X, Y, Z).