To enable a car body to be freely moved to an optional place and surely erected on the ground at the time of parking by attaching plural level jacks to the four corners of the car body so as to be erected on the ground at the lower part of the car body at the time of parking the car body and be away from the ground and housed at the lower part of the car body at the time of movement.

Among the four level jacks 3a and 3b, the lover jacks (two pieces) 3a on the front side of the car body (trailer truck) 1 are respectively freely turnably attached at the lower part of the car body 1. Also, the level jacks (two pieces) 3b on the rear side of the car body 1 are respectively vertically movably attached on the outer side of the car body 1. The respective level jacks 3a and 3b are attached so as to turn the level jacks 3a behind by a hinge 60 to be housed and to slide the level jacks 3b upwards to be housed at the time of moving the car body 1. Also, the respective level jacks 3a and 3b are vertically moved and adjusted respectively so that the car body 1 can be held horizontally to the ground 100 at the time of parking the car body 1.