The present invention relates to a small hydropower generating device including: a housing (10) installed in a water passage (60) where a fluid flows; a frame (20) inserted and installed inside the housing (10) to be separated; a water turbine (30) installed in the frame (20) to be able to rotate and rotated by the fluid passing through the housing (10); a gear box (40) increasing a rotational speed of the water turbine (30) and outputting to an upper output shaft (402); and a generator (50) producing electricity using an output of the gear box (40). The small hydropower generating device is capable of inducing a flow of the fluid to correspond to a rotational direction and specializing the shape and arrangement of blades to effectively transmit a pressure caused by the flow of the fluid, thereby increasing a rotational force and the rotational speed of the water turbine. Accordingly, an effect of maximizing the efficiency of small hydropower generation is obtained.
