PURPOSE: To give self-steering function to rear two shafts during turning by setting fitting positions for both ends of torque rods in such a manner as said rods can be fitted with a large slant in the captioned rear two shafts trunnion type suspension.

CONSTITUTION: When a vehicle turns, greater downward force works on an outside chassis frame 8 and the outside of a trunnion shaft 3 by means of centrifugal force, and joints 2a fitting torque rods 2 to the trunnion shaft 3 are largely dropped, and an angle α for torque rods 2 is increased, and further the rear first shaft 4 is pushed forward, while the rear second shaft 5 is pushed backward and separated from the shaft 4. As for the inside, on the contrary, the angle α for torque rods 2 is lessened, and the front and rear shafts 4, 5 come close to each other. Accordingly, the rear two shafts come to perform self-steering and turn smoothly. Thus, self-steering function can be given to the rear two shafts.