Abstract: A method of building an underground structure using concrete columns to be vertically installed at corners and at positions between the corners and concrete panels to be filled between adjacent concrete columns. The method comprises the steps of determining positions for the concrete columns, digging a trench for a guide composed of outer and inner frames, drilling holes for the columns, the holes being deeper than a level where the concrete panels are placed, installing the columns into the holes and setting with concrete, removing the outer frame of the guide, deepening the trench, fitting concrete panels between the columns, installing a reinforcing metal beam using concrete on the columns and panels to prevent inward buckling, and removing the inner frame of the guide after the concrete on the reinforcing beam has set.