The invention concerns a cup (12) for a bra (10) that comprises an outer shell (38) forming a recess (40) of a generally hemispherical shape and that is defined by a peripheral edge (32), characterized in that the cup (12) comprises at least an inner skin (42) forming a lining that is fixed to the peripheral edge (32) of the cup (12) and that partially covers the recess (40) formed by the outer shell (38), defining a space with the outer shell (38), and in that the inner skin (42) is designed to be tensioned when the cup (12) is placed on a breast.