A process for manufacturing an undergarment having two superimposed textiles, comprising the deposition on certain parts of reinforcements (8) comprising a thick layer of a shape-memory elastic material, the polymerization of this material and also the shaping of the textiles of the undergarment by thermoforming, characterized in that it comprises a step of depositing, on the entire surface of at least one of the textiles, a thin layer of an elastic adhesive-bonding material, and then a step of polymerizing this thin layer of adhesive bonding during the thermoforming for shaping, and in that it comprises a step of prior depositing, on the textile receiving the layer of reinforcement (8), of a barrier layer of an elastic material, which is polymerized before the depositing of this reinforcement.