To improve the function by connecting adjacent concrete blocks by connection members such as steel members pinched in respective concrete blocks in a layered state.

Connection members such as steel members or resin fiber grids 3 are held in the middle part of respective concrete blocks 4 so as to form layers to constitute a soil protection block span. Connection holes with lateral grooves are provided in a part of blocks 4 of the periphery of the block span. When laying the mat, a plurality of block spans are laid on a filter sheet 7 put on the surface of a slope. Then, slightly long reinforcements 6 used as joints and anchors in common are arranged astride on the boundaries of adjacent block spans and inserted in the connection holes, on the surface of the slope. When necessary, through holes are formed in the thickness direction in respective blocks 4 to integrally form the blocks 4, vegetation, and soil and prevent errosion. In this way, flexibility can be provided and cracks can be prevented and also the blocks can be prevented from peeling off and further, as much strength is not required, a filter sheet corresponding to purposes can be selected.