To attain miniaturization and weight reduction, sufficiently insure stroke, and improve comfortableness, by forming the cross-sectional shape of a center bracket into a pseudo-X-shape, and arranging cushioning members rhombuslikely.

A cushioning member 11 is constituted by laminating rubber pads and steel plates alternately and integratedly, and the front shape of the cushioning member in free state is formed nearly into a parallelogram. Hereby when the vehicle weight, the vibration and impact from a wheel 43 and an axle tube 8 are applied to the device, lower brackets 23 and a center bracket 25 are moved in the vertical direction, and the weight and load are supported by deformation of the cushioning members 11. Next when the dead-weight capacity to the vehicle exceeds a fixed value and moving distance of the center bracket 25 and/or the lower brackets 23 is over a fixed value, a bump stopper 28 provided on the center bracket 25 is brought into contact with brackets 21 and/or 23 so as to be deformed, and hence the cushioning members 11 and the bump stopper 28 can jointly cope with the load, the impact, and the like.