This invention relates to a torque control device for a downhole drilling assembly, the torque control device being adapted for connection to a drill bit. The torque control device includes an outer sleeve and an inner shaft, the outer sleeve being movable longitudinally relative to the inner shaft. The torque control device has a cylinder, a piston located within the cylinder, and a rotary valve to control the volume of the cylinder. The volume of the cylinder can be changed by way of the rotary valve whereby to adjust the weight on bit and thereby control the torque upon the drill bit.