A clamping device is provided for clamping a flexible packing of a cylinder of a printing press, which cylinder has an axial channel on a jacket surface. The clamping device has a clamping body (10; 20; 25), which forms a clamping gap in the channel (6) with a first opposite surface (4) for at least one end of the packing (2, 3), which end protrudes through a opening (7) of the channel (6). Two channel walls face the first opposite surface (4), and one of which forms a second opposite surface (5) and the other forms a third opposite surface (9). At the surfaces the clamping body (10; 20; 25) is supported touching the wall or walls. At least one clamping body (10; 20; 25) and the opposite surfaces (4, 5, 9) form a spring (10; 20; 14; 15). The force of elasticity of the spring (10; 20; 14; 15) tensions the clamping body (10; 20; 25) and the first opposite surface (4) toward each other in order to clamp the at least one end of the packing (2, 3) with the packing (2, 3) pulled in.