A transportable straightening beam which makes it possible to straighten deformed potshell sidewalls of different deformation resistance independently of one another is disclosed for use both with potshell carrying structure and potshell sheeting. The beam can extend between two potshell walls lying opposite one another. Each of its two end regions has a straightening jaw with a downwardly open U-profile-shaped orifice through which the straightening beam can be positioned onto the top side of the potshell sidewalls. Each straightening jaws being arranged with at least one hydraulic straightening ram parallel to the potshell bottom, and the straightening rams lying along a line of action, and such that one straightening jaw lies opposite the other straightening jaw which is carrying out the straightening work on a deformed potshell wall while being firmly braced with the top side of the potshell sidewall and serving as a captively fixed counterbearing.