A control diaphragm for controlling a fuel feed in a diaphragm carburetor of an internal combustion engine, includes a central, substantially flat feeling region, a functional region circumferentially extending around the feeling region in a concentric manner, and a peripheral fastening border for fastening the control diaphragm. The control diaphragm closes off a control chamber of the diaphragm carburetor in a sealing manner in the installed state and is operatively connected by the central feeling region to a controlling lever of the diaphragm carburetor arranged in the control chamber, which controlling lever feels the axial deflection of the feeling region in accordance with an operating-related pressure change in the control chamber. The control diaphragm is composed of a temperature- and fuel-resistant, non-elastomeric and uniformly thick plastic film, in which a plurality of concentric corrugations forming the functional region are formed so that axial deflection of the feeling region progresses in dependence on the operating-related pressure change in the control chamber in accordance with a predefined displacement/pressure characteristic curve.