To reduce the pitching and rolling by providing a floor to which a slider slidable on a straight track and a spring receiver are attached, and mounting a spring as a means to absorb and reduce the oscillation.

A spring receiver 2 is mounted on and fixed to each side of a supporting base 1. A straight track 3 is fixed to each side with the prescribed interval. A floor 4 is provided on the supporting base 1, a slider to slide on the position of the straight track 3 is mounted, and a spring receiver 6 is fixed to a central section of a lower side of the floor 4. A spring 7 is mounted respectively between the spring receiver 6 and the spring receiver 2. The slider 5 is manufactured in a U-shaped so as not to be deviated from the straight track 3, and fitted to the straight track 3. An air cylinder, a hydraulic cylinder, a shock absorber, or rubber can be used as a substitute of the spring 7. The slider is of the structure where two pieces are assembled at right angles in upper and lower stages so as to slide in the longitudinal direction and transverse direction, and absorbs the pitching and rolling at the same time.