PURPOSE: To increase the pollution removal efficiency by transferring a material toward an outlet when a tubular reaction chamber, in which the inclined angle is variable and a spiral is formed on the surface of an inner wall, is rotated about the axial line in a device for removing soil contamination by making use of microorganisms.

CONSTITUTION: The soil, from which contamination is to be removed, is introduced into a housing 11 of a tube via a supply funnel 1, and the soil is transferred in the direction of the reaction chamber 4 by the rotation of a transporting screw 2 which is freely rotatably housed thereinto. The microorganisms, enzymes and enzyme extracts are supplied from the end 12 of a piping 9, and simultaneously, nourishing substances, air or other gases are added via pipings 6, 8 into the reaction chamber 4. Further, acid and alkali are added to it to adjust the pH value. Then, a sheet 13 arranged in a spiral form into the reaction chamber 4 is provided on the inside of a wall 5, whereby an internal spiral is formed, the reaction material is transferred toward the outlet 3 when the reaction chamber 4 is rotated about the axis 14 and pollutants are decomposition-treated.