For welfare vehicles whose floor and shock absorbers are modified to enable a passenger in a wheelchair to get on and off smoothly by lowering the rear floor, the rigidity of the rear floor is insufficient. Because of this, the floor becomes deformed pressed against its stopper when the rear floor is down, and it causes excessive stress on the brackets of the fuel tank, which is secured onto the floor. A repetition of bringing the floor down may cause a crack on the fuel tank, and in the worst case, this results in fuel leakage.