To provide a method and a device for the execution of work for an underground tank, which can make the device for the execution compact and can facilitate the execution of the work for burying the tank in the ground.

A cylindrical tank body 21 is installed on the ground 22. A pressure-resistant member 24, which is composed of a plurality of supports 25 and a plurality of horizontal bars 26, is erected on the ground 22 in such a manner as to be adjacent to a peripheral wall of the tank body 21; and a jack 30 is interposed between the horizontal bar 26 of the pressure-resistant member 24 and an upper end of the peripheral wall of the tank body 21. A hole 31 for burial is excavated in the ground 22 inside the tank body 21, which is pressed and buried in the hole 31 by means of the jack 30.