A torsional vibration damper (2) according to the invention has a drive-input-side transmission element (88) which is connected to a drive input (1), a drive-output-side transmission element (92) which can be operatively connected to a drive output (86) and can be rotationally deflected relative to the drive-input-side transmission element (88), and a damping device (31) which is provided betweenthe two transmission elements and has a spring system (14) which serves to transmit a torque between the drive-input-side and the drive-output-side transmission elements and has at least one accumulator space (32) which contains a gaseous medium.; In this torsional vibration damper (2), the respective accumulator space of the spring system is operatively connected to an in each case associated liquid-medium-containing pressure space (27) of a pressure circuit (120), wherein it is at least substantially possible by means of the pressure circuit, at least in the event of a change in the torque which is to be transmitted, for an adaptation of the characteristic curve of the spring system to the changed torque to be initiated by means of a resetting of the pressure acting in the respective pressure space.