Provided is a breathing mask system, which can relieve or absorb, when worn, evensuch a force as might otherwise be generated to shift a mask cushion laterallyby a user having a moved head. The breathing mask system comprises a mask cushionfor covering a nose, a nose and a mouth, or a face entirely, a first frame connectedto the mask cushion and adapted to be fed with a breathing positive-pressure gasfrom breathing positive-pressure gas feeding means, and a second frame connectedto a head gear strap. The breathing mask system is characterized in that the maskcushion is arranged on the face side of the first frame, in that the firstframeis arranged on the face side of the second frame, in that a slide face is formed onat least one of the side of the first frame to confront the second frame and the sideof the second frame to confront the first frame, and in that the first frame andthe second frame are connected in such a state that they can slide along the slideface.
