PURPOSE: To permit buildings of comparatively low story and large lot area to be effectively constructed in soft ground.

CONSTITUTION: Sheathing works 1 of two lines are constructed at about one span along the peripheral side of a building by a trench-cut method, and the ground between the sheathing works 1 is excavated by an open-cut method. A peripheral underground structure 2 is constructed between the sheathing works 1 and at the same time a peripheral ground structure 3 is constructed on the outside of the sheathing works 1. A large roof 6 is temporarily set between the structures 3. After the underground structure 2 is completed to the ground's surface level, the structure 3 is moved sidewards by traveling and put on the structure 2. The excavation of the inside ground, the construction of the inside underground structure, the construction of ground structure, and finishing work are made.