To provide a technology for surely and rapidly preventing piping.

In a construction method for preventing the piping, a periphery of a hole 1, wherein boiling regarded as a sign of the piping occurs, is surrounded on an excavated surface 5 by a pipe material 7 so that a hydraulic gradient can be reduced for the prevention of the piping. The construction method comprises a charging process wherein iron sand with a specific gravity high enough to allow a fall against a water flow in the hole 1 is charged, and a solidification agent injection process wherein a solidification agent is injected into ground after the iron sand 10 is charged. In the solidification agent injection process, a perforated pipe 9, whose wall surface has a plurality of through-holes, is inserted into the hole 1, and the solidification agent is injected into the ground via the perforated pipe.