To generate a proper damping force using a damper complying with the running condition in different form of the vehicle.

Using a four-wheel model of a vehicle, a control device 30 controls the damping factor of the damper 14 to couple a sprung member with unsprung members by non-linear H∞ control law on the basis of a motion equation having seven degrees of freedom in total for the motion concerning the vibration in the vertical direction of the unsprung member (for example, knuckle 12, suspension arm 13, etc.) corresponding to each of the wheels WFL, WFR, WRR, WRL, the motion concerning the vibration in the vertical direction of the sprung member (for example, vehicle body 11), the motion concerning the rolling of the sprung member, and the motion concerning the pitching of the sprung member.