Abstract: A respirator mask that incorporates a respiration valve with a pressure chamber (8) between a breathing space (6) in front of the user's respiratory organs and the surrounding atmosphere. A gauge pressure in front of the user's respiratory organs during the inhalation phase as well as during the exhalation phase is established, whereupon a part of that side of the pressure chamber that faces towards the respiratory organs actuates an inhalation valve (11) in response to the movement of a regulating diaphragm (7), either directly or through a control unit (28). A detent mechanism (31), when engaged, acts counter to the regulating diaphragm (7) to detain the latter or the control unit (28) in a position in which the inhalation valve (11) is closed. When the wearer of the mask inhales, the detention provided by the detent mechanism is overcome by the force that the movement of the regulating diaphragm exerts upon the detent device during inhalation.