PURPOSE: To propose tank mounting structure avoiding metal fatigue in a chassis frame and a tank including a sub-frame so as to prevent damage caused by metal fatigue, deformation, cracking, rupture, or the like.

CONSTITUTION: In this vehicle, a tank 3 is mounted on a chassis frame 1 through a sub-frame 2. The chassis frame 1 and the sub-frame 2 are fixedly connected to each other, and the sub-frame 2 and the tank 3 are connected to each other while being supported at three points by structures P displaceable in all directions. Or the sub-frame 2 and the tank 3 are fixedly connected to each other, and the chassis frame 1 and the sub-frame 2 are connected to each other while being supported at three points by the structures P displaceable in all directions. The vertical-longitudinal-lateral torsion of the chassis frame 1 is not therefore transmitted to the tank 3 of high rigidity and heavy weight also with inertia acting thereupon, nor does the sub-frame 2 receive stress between both of them.