Abstract: To construct an underground structure having smooth wall surfaces in a simple, safe and reliable way, plates (11,12) are buried in parallel, and soil and sand (G1) between the plates is removed. If the places where the plates are to be buried are loosened in advance, they can be buried more easily. A strut member (14) is interposed between the plates, which are used as both forms and sheathing. A hollow body, together with steel plates arranged on both sides of the hollow body, is buried into the ground, the bottom of the hollow body is closed with a shutter, the hollow body is drawn up together with soil in it, leaving the steel plates in the ground, and the remaining steel plates are used as both forms and sheathing. Reinforcement bars are disposed in the groove space thereby formed, and concrete is poured to build an underground structure.