PURPOSE: To permit large-size high- or medium-size buildings having large construction lot areas to be constructed effectively.

CONSTITUTION: A construction flat lot is divided into the sections A and B, and for the preceding section A, a sheathing work 1 is constructed and the section A surrounded by the sheathing work 1 is excavated by an open cut method. An underground structure 2 is constructed in the excavated underground. At the same time, a ground structure 3 is constructed in the following section B on the ground's surface. After the structure 2 is completed to the ground's surface level, the structure 3 is moved sidewards and put on the structure 2, and the ground structure 3 is constructed in the preceding section A. A sheathing work 1' for the following section B is constructed, and the ground of the section B is excavated, followed by the construction of underground structure and ground structure and finishing work for them.