PURPOSE: To construct the structure of a temporary floor face at a low cost, improve the operating efficiency and prevent the production of waste.

CONSTITUTION: Blocks 1 consisting of a plurality of almost rectangular parallelopiped-shaped resin foams are adjoined before and behind and left and right in the horizontal direction. The blocks 1 are superposed at a plurality of stages up and down. The blocks are brought to the state, in which the blocks are displaced relatively in the horizontal direction at upper stages and lower stages, and holes 5 previously formed to the blocks 1 at the upper stages and the blocks 1 at the lower stages are communicated. Engaging tools are inserted into the communicated holes 5. Accordingly, a large number of the blocks 1 are fixed mutually as aggregate, and used as a temporary floor face.