PURPOSE: To surely support a fuel tank in vertically opened and/or closed conditions in a simple manner by attaching a bracket on the upper section of an engine, and concurrently pivotally projecting a support fixture furnished with a locking fixture out of the lower section of the fuel tank which is disposed above the engine in such a way as to be freely rocked up and down.

CONSTITUTION: In a mobile agricultural machinery, a fuel tank 2 is disposed above an engine 1, which can be rocked up and down. In this case, a bracket 3 is attached to the upper section of the engine 1, and a rocking center section A composed of a shaft 4 is arranged at the front section of the bracket 3. In addition, a locking section 7 composed of an insertion shaft and of a receiving hole is arranged at the rear section of the bracket 3. Furthermore, a support fixture 8 the lower end section of which is projected downward from the upper surface of the bracket 3 when the locking section 7 is locked, is attached to the fuel tank 2. The fuel tank 2 is so constituted that its head is freely shaked side to side in the midway of vertical rocking until at least the lower end section 9 of the support fixture 8 is positioned up to the upper surface of the bracket 3.