A damper is comprised of an actuator (A) connected to a sprung member (B) side of a vehicle, the actuator (A) including a motion converting mechanism (T) for transforming a linear motion into a rotational motion and a motor (M) to which the rotational motion resulting from the transformation by the motion converting mechanism (T) is transmitted; a hydraulic damper (E) including a cylinder (C), a piston (P) inserted slidably into the cylinder (C) and defining two pressure chambers within the cylinder (C), and a rod (R) connected at one end thereof to the piston (P), wherein a linear motion of the actuator (A) being transmitted to one of the rod (R) and the cylinder (C) while the other of the rod (R) and the cylinder (C) being connected to an unsprung member (W) side of the vehicle; and biasing means (1, 2, X, Y, Z) for biasing the hydraulic damper (E) in both compressing and extending directions.