Abstract: A holding device for a breathing mask that is fastened to a protective helmet when in use includes a fastening hook connected to a flexible, length-adjustable tightening strap that is hooked into a receptacle on the protective helmet. Stop elements that are both frictionally engaged and in positive contact prevent the accidental release of the fastening hook together with the flexibility of the tightening strap that at the same time ensures an individually adjustable fit of the mask while sliding elements arranged at an offset to the stop elements ensure automatic optimum orientation of the tightening straps. The tightening strap and the fastening hook are coupled using a retainer piece molded to the tightening strap that is held in positive contact in the recess of a grip end connected with the fastening hook.