According to the present invention, there is provided a clamping device for locking two elements, e.g. rotatable shafts, having a substantially circular cross-section. The clamping device comprises a central holding part having two partly curved sections being adapted to at least partly encircle and hold the elements, which curved sections are inversely curved. Further, the clamping device comprises an upper holding part having a partly curved section arranged being adapted to at least partly encircle and hold a first element and a lower holding part having a partly curved section being adapted to at least partly encircle and hold a second element. The central, upper and lower holding parts are adapted to co-operate to lock the elements when pressed together by means of a tightening element. The curved sections are inversely curved in relation to each other and form together with the substantially rectangular section a substantially S-shaped central part. The invention according to the present invention is capable of locking the two elements, e.g. two rotatable spindles or shafts, firmly and accurate, i.e. without any substantial tension or torsion, by means of a single tightening element, for example, a screw.
