PURPOSE: To use a rear axle commonly for several kinds of vehicles by turning the vertical positions of an attached support member which supports a shaft pin of a rear axle beam, upside down so as to adjust an axle for a vertical shift in the case of changing the size of a tire.

CONSTITUTION: A pair of support walls 2 are projected from the lower surface of a vehicle body frame 1, each consisting of upper and lower members 2a, 2b having opposite surfaces formed therein a through hole 4 in which a support rubber 5 as a support member is fitted. A shaft hole 5a is formed on the support rubber 5 at a position eccentric therefrom. Meanwhile, shaft pins 8 having a diameter equal to the bore of the shaft hole 5a are projected respectively from both front and rear sides of the center part of a rear axle beam 7 mounted at its both right and left ends with tires 6. Further, the rear axle beam 7 is supported to the vehicle body frame 1 so as to be rotatable relatively to the latter with the shaft pins 8 being fitted in the shaft holes 5a. With this arrangement, if a vertical shift occurs between the right and left tires 6, the rear axle beam 7 and the vehicle body frame are rotated, relative to each other, in order to reduce the transmission of a shock caused by the vertical shift, to the vehicle body frame.