PURPOSE: To reduce construction cost for a residential basement by placing frame-shaped blocks in desired numbers in a row through sealing members between a block having an opening on its ceiling and a block having a window and the like on its side wall, and by uniting, afterward, the blocks into one unit with wires.

CONSTITUTION: A concrete end block 1A having an opening U for a doorway to a basement and a concrete block 1B having similar opening S are formed. Frame-shaped concrete blocks 1C in desired numbers and a concrete end block 1D having a lighting window 4 and a ventilating opening 5 are provided. Then the blocks are united into one unit with seals applied to jointing faces of each block and with clamping made with anchorage grips to wires that are inserted into wire-inserting holes 11. Wiring is made using pipes embedded in walls, and thermal insulating materials are sprayed to the inside. Thereby a basement in desired extent and having desired strength can be made at low cost.