To provide a method for cleaning a contaminated ground is characterized by using a biodegradable underground pipe upon cleaning a contaminated ground to be left buried permanently allowing it to decompose by virtue of microbes in the ground into harmless substances such as carbon dioxide so as not to hinder future ground excavation, which makes it possible to use the ground effectively.

The method for cleaning a contaminated ground is characterized by comprising a step of burying a plurality of underground pipes 2 made from a biodegradable plastic in a contaminated ground, a step of cleaning the contaminated ground through the plurality of the underground pipes 2 using a specific grouting apparatus A and a subsequent step of permanently leaving the buried underground pipes 2 as they are to allow them to be decomposed by microbes in the ground to restore the once contaminated ground to an environmentally clean and natural state.