To provide an eddy current pump which is optimum to high-efficient ion separation of sewage, in a sewage treatment system for sewage, such as factory drainage and polluted underground water.

In an eddy current pump 10 employed for a sewage treatment system, a boost passage S communicating with a suction port 11a and a discharge port 11b is formed in the outer periphery of an impeller 12 contained in a housing body 11. A pair of annular permanent magnet bodies 16 fixed on the inner wall surfaces of the housing body 11 and an end plate, exposed to both sides of the impeller 12 with different magnetic pole surfaces positioned in parallel and made to face each other, generates a magnetic field vertical to a boosting passage S at an outer peripheral part. In the sewage treatment system, in the process of the flow of sewage through the boosting passage S of the eddy current pump 10, a water molecule group to cover impurity, such as cations and anions, is subdivided through the operation of a magnetic field generated in the passage S, and the impurities are separated in an exposed state.