Disposed between a sprung element and an unsprung element is a shock absorber of multi-degree variable-damping-coefficient type. The change control of the damping coefficient is carried out so that an actual damping force generated by the shock absorber can harmonize with a target damping force, Fa. The foregoing target damping force, Fa, as functions of the sprung vertical displacement velocity Xs and the unsprung vertical displacement velocity Xu, is obtained by the formula: Fa=-Xs.multidot.gs-Xu.multidot.gu, wherein both gs and gu are coefficients and the relations of gs>0; gu.gtoreq.0 hold. Thus, while controlling the sprung vertical motion, cushioning action of the wheels can be enhanced to improve traveling stabilization.