Abstract: The present invention relates to a hydropower generator for generating electricity by rotating in a fluid flow direction, the hydropower generator comprising: a central structure installed so as to be able to stand erect in water; a rotator installed on an outer circumferential surface of the central structure, and having at least one resistive plate coupled to the outer circumferential surface thereof; a rotating ring provided between the central structure and the rotator to cause the rotator to rotate around the central structure; a speed changing unit which integrally rotates by means of one side thereof coupled to the rotator; and a generator having a motor shaft coupled to the other side of the speed changing unit, and generating energy by rotation of the motor shaft, wherein the resistive plate is located in the water and generates resistive force according to the flow of water while the rotator rotates, such that energy is generated from the generator.