PURPOSE: To make it possible to show a drainage function in a laminated state and to drain the rain and the like into the foundation on the underside or the outside of the side by forming an appropriate number of perforated holes lengthwise and/or crosswise on foaming blocks of synthetic resin.

CONSTITUTION: A number of perforated holes 2 are formed lengthwise or crosswise on foaming resin blocks 1. In case of constructing a laminated structure 10, foaming blocks are so piled up in the vertical direction that the perforated holes 2 of the foaming resin blocks 1 fit with each other. According to the constitution, in the execution at a watery site, the buoyance of resin blocks 1 can be reduced to facilitate the construction of a piling up of foaming blocks and the execution of laying them underground.