A continuously lockable adjustment device for immobilizing elements which are movable relative to each other includes a stepped cylinder having a first cylinder step and a second cylinder step, the second cylinder step having a larger cross-sectional area than the first cylinder step, a stepped piston having a first piston step guided in the first cylinder step and a second piston step guided in the second cylinder step, and a piston rod connected to the piston opposite the first piston step and extending sealed off out an end of the cylinder. The cylinder has a first working space and a second working space separated by the piston and filled with a working fluid in which the piston can be displaced axially, thereby displacing working fluid from one working space to the other working space.