To prevent malfunction of a sensor which is installed on a jack device caused by vibration due to traveling, and preclude noise generated resulting from vibration.

A high lift working vehicle concerned is equipped with a boom 2 installed on a vehicle body 1 in such a way as rising and falling, a bucket 3 installed at the tip of the boom 2, and jacks 4, 5 installed at the sides of the front and rear of the vehicle body 1 for supporting it. Among them the jacks 5 on both sides of the vehicle rear have jack bodies 5b which are located in a cargo box 1a, wherein the bottom of an expansion part 5a or each jack 5b is arranged penetratively from the bottom surface of the cargo box 1a and the jack bodies 5b are mounted in such a condition as energized in one direction by an energizing member 55. At least the rear jack device 5 is arranged so that the tops of the jack bodies 5b are pivoted in such a way as swingable oscillatively, and the jack bodies 5b are mounted in such a way as energized in on direction by the energizing member 55.