PURPOSE: To increase adhesion effect of blocks to a sheet material and prevent mal-effects of the sheet material on soil, by interposing an adhesive non- vulcanized rubber between the underface of the block and the upper face of the sheet material.

CONSTITUTION: Blocks 2 are stuck on a sheet material 1 with an adhesive as a group. Non-vulcanized butyl rubber 3 is used as the adhesive to increase the adhesive effect on the sheet. Next, a plurality of blocks 2 are rranged on the sheet 1. A number of parts are laid down both lengthwise and crosswise so that the horizontal rotary support protrusion 22 is superposed with the horizontal rotary support groove 21 in the adjacent parts to construct a continuous erosion-proof structure by a number of blocks 2. The sheet material 1 is made of polypropylene sheet having (1-100)×10-2cm/sec in permeability coefficient in order to retain the quality of soil coating the sheet 1, suitable for plant and underground microbes.