To provide a method for culturing microorganisms capable of efficiently carrying out the cleaning treatment of a polluted soil, underground water or the like polluted with an organic chlorine compound in a short period at low costs, and to provide a method for cleaning the polluted soil and the underground water.

The microorganisms capable of efficiently carrying out the cleaning treatment of the polluted soil, the underground water or the like polluted with the organic chlorine compound in a short period at low costs can be obtained by culturing microorganisms capable of degrading the organic chlorine compound in the presence of at least one of soil and a material containing a humus substance. The cleaning treatment of the polluted soil, the underground water or the like polluted with the organic chlorine compound can efficiently be carried out in a short period at low costs by using the microorganisms cultured in the presence of at least one of the soil and the substance containing the humus substance, and degrading the organic chlorine compound, or by adding at least one of the soil and the substance containing the humus substance.