The invention relates to a delordosation device for users of a rehabilitation appliance, in particular for the verticalization of a sit/stand exercise machine or a wheel chair with a seating area and support aids for a user, the seating area supported in a swiveling manner swiveling for verticalization. To avoid hyperlordosis while patients with a restricted mobility are being straightened up in rehabilitation measures or a verticalization in a sit/stand exercise machine 1 or wheel chair, it is provided that the seating area is supported in a swiveling manner, and at least a portion of the seating area is mounted in a movable manner. Thus, a pelvis rotation can be initiated during verticalization, whereby hyperlordosis is avoided.