PROBLEM TO BE SOLVED: To provide a reinforcing method capable of securing the stability of an existing masonry wall at a low cost.
SOLUTION: The reinforcing method is applied to the existing masonry wall 16 of a wet masonry system filling back-filling concrete 15 between stone blocks 14 piled up in the vertical direction so as to adjoin a plurality of stone blocks 14 to one another by making a backing cobble stone layer 12 intervene in the front of an inclined bedrock 10, a drilling hole 18 reaching the backing cobble stone layer 12 from the front of the masonry wall 16 is formed, and grout 20 is injected into the drilling hole 18 to locally provide a reinforced section 22 solidifying the grout 20. The drilling hole 18 is formed in a joint section of the stone blocks 14, and it is zigzag-placed in every other of adjoining joint sections in vertical and longitudinal directions. The drilling hole 18 is formed from the front side of the masonry wall 16 by a small drilling machine. Partial improvement and a reinforced effect can be obtained by providing the local reinforced section 22, and the fragility of the back-filling concrete 15 is reinforced to obtain the stability of the existing masonry wall 16.