To obtain a fiber sheet for reinforcing structure, suitable for reinforcement of building members such as concrete by forming a sheet-like material from a specific polyoxymethylene monofilament yarn and a yarn having finer diameter than that of the above monofilament yarn.

A polyoxymethylene monofilament 3 having 0.3-2 mm average line diameter and 20-150 GPa tensile modulus is aligned at intervals in horizontal direction and woven or knitted by using a yarn such as nylon, polyester, polyethylene or glass fiber having finer diameter than that of the above polyoxymethylene monofilament to form a sheet and crossed parts of yarn of the resultant sheet are fused by heat, radio frequency, etc., to provide the objective sheet-like material 2.