A torsional rigidity control device capable of controlling a moment provided to stabilizers (1f) and (1r) against the moment based on an external moment loaded from the outside to the stabilizers (1f) and (1r), comprising a moment variable mechanism for varying the moment loaded on the stabilizers (1f) and (1r) by regulating a fluid pressure supplied from a fluid pressure source driving rotary actuators (2f) and (2r) connected to the intermediate parts or one ends of the stabilizers (1f) and (1r) or the cylinders (51f) and (51r) connected to one ends of the stabilizers (1f) and (1r), characterized in that the necessary value of the fluid pressure for driving the rotary actuators (2f) and (2r) or the cylinders (51f) and (51r) is calculated based on the value of the external moment, the value of the fluid pressure supplied to the rotary actuators (2f) and (2r) or cylinders (51f) and (51r) is compared with the necessary value of the fluid pressure, and based on the compared result, the fluid pressure is regulated to control the moment, whereby a stable torsional rigidity can be developed by stabilizing a fluid pressure in a pressure chamber to increase a riding comfortableness at the time of rolling of a vehicle even when the device is mounted on the vehicle.