Abstract: A holding device for holding objects has a substantially cupshaped housing having an open side, an elastic element connected with the housing and closing the open side, at least one projection extending from the elastic element inwardly of the housing, a turning element extending through the projection and having a portion extending outwardly of the housing, the turnable element being turnable by a user who grasps the outer portion of the turning element between a first position in which it concave toward the diaphragm and the diaphragm is concavely displaced into the housing and a second position in which the turning element is convex toward the housing and the diaphragm convexly bulges out of the housing so as to press out air between the diaphragm and a surface in which the holding device is to be attached, and elements provided on the housing for retaining an object.