To crack the contaminated groud region as widely as possible by freezing the region and sucking the intrasoil gas from the ground to extract the contaminated vapor.

A gas or liq. pressure injection line 2 using a compressor 1, etc., is prepared in the contaminated soil region 8 to be restored previously set according to information of the boring test, etc. A freezing pipe 5 for supplying a refrigerant and a pressure injection pipe 2 or further a suction pipe 6 connected to a suction pump 7 are built in a well bored in the region. An antifreeze (aq. calcium chloride soln.) called a brine is cooled to -20 to -30°C and introduced into the freezing pipe 5 through a circulating pump to cool the ground. The frozen ground is then naturally thawed to ordinary temps. or heated and rapidly thawed, and the gas in the soil is sucked to extract the contaminated vapor.