PURPOSE: To make the suspension device applicable to a U-shaped chassis frame having an inner frame on the inside thereof, by supporting via shafts walking beams at lower positions of brackets mounted on a U-shaped chassis frame, supporting via shafts upper ends of torque rods by the brackets, and supporting via shafts tires by retainers at both ends of the walking beams.

CONSTITUTION: A suspension device is separately equipped to both side portions 4a of a chassis frame 4a and mounted to an F face thereof. The central portion of a walking beam 6 biased toward one of both side faces 5a at a lower portion of a bracket 5 is supported by a shaft 7. The upper ends of two torque rods 8 are supported at positions biased toward the side faces 5a supporting the walking beam 6 and at upper positions of the bracket 5. On the other hand, two tires 9 are equipped to positions biased toward the side faces 5a different from the side faces 5a supporting the walking beam, which tires 9 are supported by retainers 10 secured to both ends of the walking beams 6.