Abstract: Adjustment device for tiltable sitting furniture with a stand (1) and a seat board (9) pivoting at the front side of the stand, as well as a driving device (16) arranged to convey the seat board (9) its tilt motion, where the seat board (9) at the front is pivotally arranged at the front edge of a fork (7) articulatedly suspended via arms (5) at the front part of the stand, which fork is in rear the part of the stand and at the rear is guided slidably against a slide rail (10), and the driving device (16) of which via a pressure arm (12) pivotally arranged at the stand transfers motion to the seat board, in addition to the pressure arm (12) is pivotally connected a control bar (19) between its pivot point and its end with the seat board, which control bar during work of the driving device (16) with its front part first is brought to bearing on a position adjustable backing roller (21) connected to the arms (5) of the fork (7) and subsequently with its rear part (23) in different positions adjustable against a