PURPOSE: To speed up construction work by a method in which short pillars set in holes for independent foundation are connected with underground beams loosely penetrated into trenches, the underground beams are covered with concrete, and the pillars of a building structure are placed and fixed to the upsides of the short pillars.

CONSTITUTION: Concrete is placed into holes 13 for independent foundation to form an independent foundation 19, and short pillars 23 for underground steel beams are fixed with anchor bolts 21 and nuts 29 to the upside of the foundation 19. The short pillars 23 are connected with underground beams 39 loosely inserted into trenches 15 for beam and the underground beams 39 are covered with concrete C. Soil and sand are embedded into the apertures between the holes 13 and the foundation 19 and between the trench 15 and the beams 39. A building strucrure 31 is placed on the upper plate 25 of the short pillars 23, and the connecting plate 49 of the pillars 45 of the structure 31 and the upper plate 25 are fixed with bolts 51 and nuts 53.