To shorten the overall length of a trailer coupled vehicle through simple structure.

This structure is formed that a fixed bar 5 removably mounted on a coupling bar 4 arranged at the rear part of a vehicle 2 is fixed in a manner to extend in the direction of a car width, the base 3 for a load-carrying platform of a trailer 1 is pivotally coupled through a hook 6 arranged in the middle of the coupling bar 4, the parts in the vicinity of the two ends of the axle 9 of the trailer 1 and the parts in the vicinity of the two ends of the fixed bar 5 are intercoupled through a pair of right and left suspension arms 11, the king pin shafts K of the right and left wheels 7 of the trailer 1 are arranged on the front side in an advancing direction based on a grounding part S, and coupling of the suspension arm 11 with the fixed bar 5 is performed oscillatorily only in the vertical direction of the vehicle 1. Pitching and rolling are allowed through vertical oscillation movement of the suspension arm, coping with yawing is effected by steering the wheels of the trailer, a coupling angle is prevented from occurring during running, and an overall length is shortened, whereby maneuverability and drivability during traction running are improved.