To provide an apparatus and method for dehydration treatment of water-containing oil, which can efficiently remove water from the water-containing oil, and to provide a wind power generator.

An apparatus for dehydration treatment of water-containing oil is provided, the apparatus comprising: a dehydrator body 13 in which a prescribed amount of a water-containing oil 12 from a storage tank 11 is being fed; electrolysis electrodes composed of a pair of a positive electrode 14 and a negative electrode 15 that are disposed with a prescribed space between each other in the water-containing oil being fed into the dehydrator body 13; and a power source 16 for supplying electric current to the positive electrode 14 and the negative electrode 15. Electric current is supplied to the positive electrode 14 and the negative electrode 15 so as to electrolyze water in the oil by electrolysis.