PURPOSE: To improve execution efficiency by drilling a through hole, which penetrates through upper and lower surfaces, in a block main unit and/or a protrusive part, provided in the reverse side of the block main unit, while inserting a bar material and providing a connecting part in the upper and lower end parts.

CONSTITUTION: A block main unit 1 is formed of a protrusive part 1a, through hole 1b and a bar material 2 provided with a thread 2a in the upper and lower end surfaces. Next, an anchor bolt 4 is fixed to a bottom board 3, and a coupler 5 is screwed to an upper end exposed thread part of the anchor bolt 4. Then, the main unit 1 in the first step is set up on the bottom board 3, and the lower end thread 2a of the bar material 2 is screwed in and connected to the coupler 5. The main unit in the second step is piled on the main unit 1 in the first step with the bar material 2 connected, when piling is completed to the predetermined height, the bar material 2 is tightened by a jack, and the block main units are firmly integrally formed. In this way, work efficiency can be improved.