PURPOSE: To reduce the equipment cost and running cost and to increase ocean current MHD power generation efficiency, by combining a superconducting high-gradient magnetic separating system with an ocean current MHD power generating system.

CONSTITUTION: When sea water containing a conductive agent and a magnetic agent added and mixed by an adding device 5 for conductive and magnetic agents flows inside a sea water pipe 1, electric power is obtained with upstream side electrode plate 3 at first. Next, a down stream side magnetic filter 4 recovers separation object materials (marine resources, harmful substances, etc.) which have absorbed the added magnetic agent. This makes it possible to decrease the equipment cost and running cost greatly and to increase ocean current MHD power generation efficiency.