To simply and inexpensively regenerate insulating oil of an electric apparatus after use and in use.

An insulating oil regeneration device 1 is provided with a first separation tank 3 and a second separation tank 4. The first separation tank 3 is a sealed system and brings insulating oil introduced from the electric apparatus 2 into contact with water or a salt aqueous solution to elute moisture and a salt content included in the insulating oil in the phase of the water or the salt aqueous solution. The second separation tank 4 brings the insulating oil introduced from the first separation tank 3 into contact with a polar solvent to elute an organic halogen substance included in the insulating oil in the phase of the polar solvent. The insulating oil separated by the second separation tank 4 is returned to the electric apparatus 2 by an insulating oil returning means having a pump P3.