To provide a soil decontamination method for efficiently removing contaminants from a soil contaminated with organic substances.

This decontamination method of the soil contaminated with the organic substances comprises a process (1) where electrodes are inserted into a soil w which includes a water impermeable layer, underground water on the layer, and a water bearing layer on the underground water and is contaminated with the organic substances, at intervals and an injection pipe is inserted into the surface of the soil until reaching the upper part of the water impermeable layer, a process (2) for pouring a conductive material or a liquid containing the material into the injection pipe, and a process (3) for applying a voltage between the electrodes to heat the water impermeable layer, and the underground water and/or water in the water bearing layer.