The invention relates to a securing and locking unit (1) for displaceable and pivotable doors and/or walls (20) that are movably guided by means of rollers and/or in a roller guide rail (30). The unit is characterized by being attached to the upper part (2) of the roller guide rail (30), to the central part (3) of the doors and/or walls (20), and hte lower part (4) of the doors or walls (20). The unit is provided with a fastening element (5) used for releasing or locking the doors or walls (20). Furthermore, the invention relates to the partition wall system with two or more displaceable and pivotable doors and/or walls (20), which are secured with such an adjustment and locking unit (1).