To detect the relative displacement between an unsprung and a sprung of a vehicle in simple constitution.

In a vehicle including an absorber adapted to generate damping force between the sprung and the unsprung of the vehicle by rotating a ball screw mounted on the sprung of the vehicle engaged with a ball screw nut mounted on the unsprung of the vehicle by a rotating motor, an ECU mounted on the vehicle obtains a rotating angle of the motor detected by a rotating angle sensor (S10), and calculates a stroke of the ball screw from the rotating angle (S12). Further, the relative speed is calculated by time differentiation of the stroke (S14), and the relative acceleration is calculated by time differentiation of the relative speed (S16). The ECU controls the attitude of a car body on the basis of these values (S18).