To prevent generation of cracking at the time of solidification shirinkage of mortar by mounting a plurality of U shaped members erected on a lower steel reinforcement member on an upper steel reinforcement member, installing a reinforcing metal net at the position of the lower steel reinforcement member, and spraying mortar thereonto and performing fixed the same.

A reinforcing metal net 6 is installed over a slope surface, and a plurality of U shaped members 3 are errected at an interval in the longitudinal direction of a lower steel reinforcement member 2 placed in parallel therewith. While the intermediate part between both legs of the U shaped member 3 is fixed to the member 2 and a primary frame 5 is installed in order on the slope surface, the lower ends of both legs of U shaped member 3 of the frame 5 are erected on the slope surface, and the reinforcement metal net 6 is attached to the height position of lower steel reinforcement member 2 attached to the intermediate heigh position between both legs of the member 3. Over the upper part of the member 3 an upper steel reinforcement member is attached to form a form 1, and anchor 7 is placed at the proper position of the form 1 to fix it to the slope surface, then mortar or vegitation substrate material 8 is sprayed onto the frame 1 and the net 6 and it is solidified.