PURPOSE: To improve the riding comfortableness of a vehicle by quickly converging vibration of a sprung member.

CONSTITUTION: Damping force F of a shock absorber 14 against vibration of a car body is detected by a damping force sensor 21, and a displaced amount L in a vertical direction by vibration of the car body is detected by a stroke sensor 22. In a microcomputer 23, the displaced amount L is differentiated by a program process to calculate a speed V of a piston 14a of the shock absorber 14, also to calculate power F.V by the shock absorber 14 based on these damping force F and speed V. So as to maximize the power F.V, an opening of a solenoid valve 14d, that is, damping force by the shock absorber 14 is controlled to be changed. In this way, vibration of the car body is efficiently absorbed, to quickly damp this vibration.