Disclosed is a flow rate controller in which a clear width (6) of a control gap (4) between a main part (3) and a control element (2), which is deformable according to the pressure in order for the flow rate through the control gap (4) to be kept constant, can be adjusted as a result of the fact that at least one supporting element that adjusts the clear width (6) of the control gap (4) is designed to be movable relative to a main part (3).