PURPOSE: To facilitate piling-up and setting of unit blocks and to reduce welding force to increase the economical effect by opening a large number of through-holes in the circumferential direction of the skeleton of unit blocks of a well, and spouting compressed air or water from spouts to prevent the adherence to earth.

CONSTITUTION: Reaction members 7 and 7 of a double-U steel, etc. are driven to the outside of a well settling position, a unit block 1a is placed thereon, the lower part thereof is excavated to move earth and, at the same time, force-fit and forced settlement of the block 1a is made by a force-fit device 8 interlocked with the reaction members 7 and 7. After that, the lower ends of through-holes 4 are blocked, and com pressed air or pressure water is supplied from the upper end. The compressed air or water is spouted between the circumferential surface of the unit block 1a and earth from spouts 5 to flow upward, and the adherence of the circumferential surface of the unit block 1a and earth is prevented. In addition, PC steel bars 6 are inserted into adherence holes 3, the lower ends of them are fixt to the block 1a, and settling work is repeated while piling up subsequently unit blocks 1a - n to construct the well. According to the constitution, temporary reaction members or a small sized pressure device can be available, and economic efficiency can be promoted.