The mask (1) has a flexible membrane (13) interposed between a flexible bearing element (11) and a patients face (9). A multi-perforated inner skirt (14) is inserted on the element via one of its two contours (14E) and surrounded by the membrane. A free contour (14I) of the skirt extends in direction of an inner chamber (3) of a hollow mask body (2). The membrane and the skirt are configured such that respiratory gas (7) from a respiratory gas inlet (4) of the chamber is adapted to cross perforations (15) of the skirt to stretch the membrane and apply the membrane tightly against the face. The bearing element is in the form of an inflatable bead or a closed pore foam bead.
