PURPOSE: To improve the operation stability by linking a leaf spring for supporting a rear axle on a frame, an air spring and a torque rod of a special form.

CONSTITUTION: A rear suspension 10 is assembled by a leaf spring 11, an air spring 12 and torque rods 13. The leaf spring 11 is disposed at a suitable space in the cross direction of a frame 30, the front end thereof is hinge-connected to the frame, and a rear axle 32 is fixedly connected to the rear end of the leaf spring to be supported on the frame 30. The air spring 12 is disposed at a suitable space in the cross direction of the frame 30 in the rear of the rear axle 32 to support the rear axle on the frame 30. The torque rods 13 are disposed above the rear axle 32 in such a manner as to become narrower in the rear so that the instantaneous center C is positioned in the rear of the axis 0 of the rear axle 32, thereby connecting the rear axle 32 to the frame 30 at a suitable space in the cross direction of the frame 30.