PURPOSE: To lessen the variation of a body height and the inclination or the body during travel on a rugged road and also improve the operator's riding comfortableness.

CONSTITUTION: The central parts of longitudinal members 11 fitting wheels are supported by supporting mechanisms 12 so as to be vertically movable, at both right and left side faces of a vehicle body 10 respectively. And the front wheels 13 and the rear wheels 14 are provided near the front and rear ends of the longitudinal members 11 fitting these wheels and an equalizer bar 15 is equipped on the body 10 so as to be freely movable in both right and left hands. Both ends of the equalizer bar 15 is connected to the longitudinal member 11 fitting the wheels through the upper and lower springs 18, 19.